# Coding Challenges

A weekly Coding Challenge to help software engineers level up.

This is one page of public article previews, not the complete archive. Follow Next page to continue. Summaries are not the original full articles.

## Coding Challenge #136 - Hyperfine

DevFeed: [Coding Challenge #136 - Hyperfine](<https://devfeed.tech/articles/coding-challenge-136-hyperfine-29211.md>)

Original publisher: [Read original article](<https://codingchallenges.substack.com/p/coding-challenge-136-hyperfine>)

Author: John Crickett

Published: 2026-09-12T08:03:11Z

Content type: tutorial

Language: en

Sources: [Coding Challenges](<https://devfeed.tech/sources/coding-challenges.md>)

Topics: [benchmarking](<https://devfeed.tech/topics/benchmarking.md>), [coding](<https://devfeed.tech/topics/coding.md>), [Command-line interface](<https://devfeed.tech/topics/cli.md>), [Processes](<https://devfeed.tech/topics/processes.md>)

Tags: [benchmarking](<https://devfeed.tech/tags/benchmarking.md>), [coding](<https://devfeed.tech/tags/coding.md>), [command-line](<https://devfeed.tech/tags/command-line.md>), [performance](<https://devfeed.tech/tags/performance.md>), [process](<https://devfeed.tech/tags/process.md>), [programming](<https://devfeed.tech/tags/programming.md>)

### AI overview

A coding challenge asks readers to build a command-line benchmarking tool modeled on hyperfine. The tool should run commands repeatedly, measure execution time and variation, compare commands, export results, and warn about unreliable measurements.

### Source excerpt

This challenge is to build your own benchmarking tool.

## Coding Challenge #135 - Voice Dictation App

DevFeed: [Coding Challenge #135 - Voice Dictation App](<https://devfeed.tech/articles/coding-challenge-135-voice-dictation-app-29210.md>)

Original publisher: [Read original article](<https://codingchallenges.substack.com/p/coding-challenge-135-voice-dictation>)

Author: John Crickett

Published: 2026-09-05T08:01:16Z

Content type: tutorial

Language: en

Sources: [Coding Challenges](<https://devfeed.tech/sources/coding-challenges.md>)

Topics: [Code Challenge](<https://devfeed.tech/topics/code-challenge.md>), [Programming](<https://devfeed.tech/topics/programming.md>), [AI Development](<https://devfeed.tech/topics/ai-development.md>), [Accessibility](<https://devfeed.tech/topics/accessibility.md>), [Operating system](<https://devfeed.tech/topics/operating-system.md>)

Tags: [accessibility](<https://devfeed.tech/tags/accessibility.md>), [ai](<https://devfeed.tech/tags/ai.md>), [audio](<https://devfeed.tech/tags/audio.md>), [coding](<https://devfeed.tech/tags/coding.md>), [os](<https://devfeed.tech/tags/os.md>), [programming](<https://devfeed.tech/tags/programming.md>), [ui-automation](<https://devfeed.tech/tags/ui-automation.md>), [voice](<https://devfeed.tech/tags/voice.md>)

### AI overview

A Coding Challenge tutorial for building a private voice dictation app that runs entirely on the local computer. It covers audio capture, local speech recognition, text cleanup, spoken formatting commands, custom dictionaries, history, and inserting dictated text into the focused application without network requests.

### Source excerpt

This challenge is to build your own voice dictation app.

## Coding Challenge #134 - Agentic Engineering Graph

DevFeed: [Coding Challenge #134 - Agentic Engineering Graph](<https://devfeed.tech/articles/coding-challenge-134-agentic-engineering-graph-29209.md>)

Original publisher: [Read original article](<https://codingchallenges.substack.com/p/coding-challenge-134-agentic-engineering>)

Author: John Crickett

Published: 2026-08-29T08:01:12Z

Content type: tutorial

Language: en

Sources: [Coding Challenges](<https://devfeed.tech/sources/coding-challenges.md>)

Topics: [agentic-coding](<https://devfeed.tech/topics/agentic-coding.md>), [Orchestration](<https://devfeed.tech/topics/orchestration.md>), [coding](<https://devfeed.tech/topics/coding.md>), [MCP Server](<https://devfeed.tech/topics/mcp-server.md>), [Langgraph](<https://devfeed.tech/topics/langgraph.md>), [MCP](<https://devfeed.tech/topics/mcp.md>), [Chaos Engineering](<https://devfeed.tech/topics/chaos-engineering.md>), [ide](<https://devfeed.tech/topics/ide.md>)

Tags: [agent](<https://devfeed.tech/tags/agent.md>), [agentic](<https://devfeed.tech/tags/agentic.md>), [agentic-coding](<https://devfeed.tech/tags/agentic-coding.md>), [agentic-engineering](<https://devfeed.tech/tags/agentic-engineering.md>), [ci](<https://devfeed.tech/tags/ci.md>), [code](<https://devfeed.tech/tags/code.md>), [distributed-systems](<https://devfeed.tech/tags/distributed-systems.md>), [langgraph](<https://devfeed.tech/tags/langgraph.md>), [news](<https://devfeed.tech/tags/news.md>), [orchestration](<https://devfeed.tech/tags/orchestration.md>), [review](<https://devfeed.tech/tags/review.md>), [sonarqube](<https://devfeed.tech/tags/sonarqube.md>), [systems](<https://devfeed.tech/tags/systems.md>)

### AI overview

A coding challenge guides readers through building an agentic engineering graph: a small orchestration system that runs an autonomous coding loop of planning, coding, testing, review, and retry. It uses scripts and files for dispatch and persisted state, adds a deterministic Sonar static-analysis quality gate, and then replaces it with an AI-augmented review node using the SonarQube MCP Server.

### Source excerpt

This challenge is to build your own agentic engineering graph.

## Coding Challenge #133 - Particle Playground

DevFeed: [Coding Challenge #133 - Particle Playground](<https://devfeed.tech/articles/coding-challenge-133-particle-playground-29208.md>)

Original publisher: [Read original article](<https://codingchallenges.substack.com/p/coding-challenge-133-particle-playground>)

Author: John Crickett

Published: 2026-08-22T08:01:30Z

Content type: tutorial

Language: en

Sources: [Coding Challenges](<https://devfeed.tech/sources/coding-challenges.md>)

Topics: [Simulation](<https://devfeed.tech/topics/simulation.md>), [Cellular automaton](<https://devfeed.tech/topics/cellular-automaton.md>), [coding](<https://devfeed.tech/topics/coding.md>), [creative coding](<https://devfeed.tech/topics/creative-coding.md>), [Graphics](<https://devfeed.tech/topics/graphics.md>), [Canvas](<https://devfeed.tech/topics/canvas.md>)

Tags: [canvas](<https://devfeed.tech/tags/canvas.md>), [coding](<https://devfeed.tech/tags/coding.md>), [creative-coding](<https://devfeed.tech/tags/creative-coding.md>), [graphics](<https://devfeed.tech/tags/graphics.md>), [programming](<https://devfeed.tech/tags/programming.md>), [real-time](<https://devfeed.tech/tags/real-time.md>), [simulation](<https://devfeed.tech/tags/simulation.md>)

### AI overview

A coding challenge guides readers through building a 2D particle playground with two simulation engines: a force-based particle system and a cellular automaton. The project combines materials such as sand, water, and fire with a fireworks display whose embers can ignite the material grid.

### Source excerpt

This challenge is to build your own particle playground.

## Four Days Left to Enter the Ready, Spec, Ship Hackathon

DevFeed: [Four Days Left to Enter the Ready, Spec, Ship Hackathon](<https://devfeed.tech/articles/just-four-days-left-to-enter-the-ready-spec-ship-hackathon-29213.md>)

Original publisher: [Read original article](<https://codingchallenges.substack.com/p/just-four-days-left-to-enter-the>)

Author: John Crickett

Published: 2026-08-19T08:02:04Z

Content type: opinion

Language: en

Sources: [Coding Challenges](<https://devfeed.tech/sources/coding-challenges.md>)

Topics: [Hackathon](<https://devfeed.tech/topics/hackathon.md>), [Kiro](<https://devfeed.tech/topics/kiro.md>), [agentic-coding](<https://devfeed.tech/topics/agentic-coding.md>)

Tags: [agentic-coding](<https://devfeed.tech/tags/agentic-coding.md>), [build](<https://devfeed.tech/tags/build.md>), [coding](<https://devfeed.tech/tags/coding.md>), [hackathon](<https://devfeed.tech/tags/hackathon.md>), [kiro](<https://devfeed.tech/tags/kiro.md>), [project](<https://devfeed.tech/tags/project.md>)

### AI overview

A reminder that four days remain to enter the Ready, Spec, Ship Hackathon. Participants may enter individually or in teams of up to three, submit multiple projects, and receive free Kiro credits if their entries are verified. The article also describes the $9,600 prize pool and submission deadline.

### Source excerpt

What will you build and could you win a prize?

## Coding Challenge #131 - Automated Code Review Agent

DevFeed: [Coding Challenge #131 - Automated Code Review Agent](<https://devfeed.tech/articles/coding-challenge-131-automated-code-review-agent-29207.md>)

Original publisher: [Read original article](<https://codingchallenges.substack.com/p/coding-challenge-131-automated-code>)

Author: John Crickett

Published: 2026-08-15T08:01:51Z

Content type: tutorial

Language: en

Sources: [Coding Challenges](<https://devfeed.tech/sources/coding-challenges.md>)

Topics: [Code Challenge](<https://devfeed.tech/topics/code-challenge.md>), [GitHub Copilot code review](<https://devfeed.tech/topics/github-copilot-code-review.md>), [pull-requests](<https://devfeed.tech/topics/pull-requests.md>), [Pull Request](<https://devfeed.tech/topics/pull-request.md>), [Orchestration](<https://devfeed.tech/topics/orchestration.md>), [GitHub](<https://devfeed.tech/topics/github.md>), [Artificial Intelligence](<https://devfeed.tech/topics/ai.md>), [YAML](<https://devfeed.tech/topics/yaml.md>), [engineering-culture](<https://devfeed.tech/topics/engineering-culture.md>)

Tags: [agent](<https://devfeed.tech/tags/agent.md>), [ai](<https://devfeed.tech/tags/ai.md>), [automated](<https://devfeed.tech/tags/automated.md>), [code-review](<https://devfeed.tech/tags/code-review.md>), [coding](<https://devfeed.tech/tags/coding.md>), [collaboration](<https://devfeed.tech/tags/collaboration.md>), [github](<https://devfeed.tech/tags/github.md>), [orchestration](<https://devfeed.tech/tags/orchestration.md>), [pull-request](<https://devfeed.tech/tags/pull-request.md>), [run](<https://devfeed.tech/tags/run.md>), [tools](<https://devfeed.tech/tags/tools.md>), [triggers](<https://devfeed.tech/tags/triggers.md>), [workflow](<https://devfeed.tech/tags/workflow.md>), [yaml](<https://devfeed.tech/tags/yaml.md>)

### AI overview

Coding Challenge #131 asks readers to build an automated code review agent that reviews pull requests against team coding guidelines and posts findings as comments. The challenge covers retries, event triggers, concurrency control, large pull requests, static analysis tools, and lookup capabilities.

### Source excerpt

This challenge is to build your own code review agent.

## Coding Challenge #130 - Sort Visualiser

DevFeed: [Coding Challenge #130 - Sort Visualiser](<https://devfeed.tech/articles/coding-challenge-130-sort-visualiser-29206.md>)

Original publisher: [Read original article](<https://codingchallenges.substack.com/p/coding-challenge-130-sort-visualiser>)

Author: John Crickett

Published: 2026-08-08T08:01:19Z

Content type: tutorial

Language: en

Sources: [Coding Challenges](<https://devfeed.tech/sources/coding-challenges.md>)

Topics: [Sorting](<https://devfeed.tech/topics/sorting.md>), [Algorithm](<https://devfeed.tech/topics/algorithm.md>), [coding](<https://devfeed.tech/topics/coding.md>), [ui](<https://devfeed.tech/topics/ui.md>), [implementation](<https://devfeed.tech/topics/implementation.md>)

Tags: [algorithms](<https://devfeed.tech/tags/algorithms.md>), [animation](<https://devfeed.tech/tags/animation.md>), [coding](<https://devfeed.tech/tags/coding.md>), [implementation](<https://devfeed.tech/tags/implementation.md>), [sorting](<https://devfeed.tech/tags/sorting.md>), [tool](<https://devfeed.tech/tags/tool.md>), [ui](<https://devfeed.tech/tags/ui.md>)

### AI overview

Coding Challenge #130 asks readers to build a sorting algorithm visualiser that animates how eight classic algorithms operate on arrays. The project also provides practice with UI rendering, animation timing, and clean abstractions, while allowing choices such as algorithm, sample size, data order, display mode, and animation speed.

### Source excerpt

This challenge is to build your own tool to visualise how sorting algorithms work.

## Ready, Spec, Ship Hackathon Announces $9,600 Prize Pool and Kiro Credits

DevFeed: [Ready, Spec, Ship Hackathon Announces $9,600 Prize Pool and Kiro Credits](<https://devfeed.tech/articles/join-the-ready-spec-ship-hackathon-hackathon-29212.md>)

Original publisher: [Read original article](<https://codingchallenges.substack.com/p/join-the-ready-spec-ship-hackathon>)

Author: John Crickett

Published: 2026-08-04T15:03:54Z

Content type: article

Language: en

Sources: [Coding Challenges](<https://devfeed.tech/sources/coding-challenges.md>)

Topics: [Hackathon](<https://devfeed.tech/topics/hackathon.md>), [Kiro](<https://devfeed.tech/topics/kiro.md>), [agentic-coding](<https://devfeed.tech/topics/agentic-coding.md>)

Tags: [agentic](<https://devfeed.tech/tags/agentic.md>), [agentic-coding](<https://devfeed.tech/tags/agentic-coding.md>), [coding](<https://devfeed.tech/tags/coding.md>), [hackathon](<https://devfeed.tech/tags/hackathon.md>), [kiro](<https://devfeed.tech/tags/kiro.md>)

### AI overview

An announcement for the Ready, Spec, Ship Hackathon, sponsored by Kiro. Participants may enter alone or in teams of up to three, submit multiple projects, and receive Kiro credits for verified entries; submissions close on 23 August.

### Source excerpt

Try Kiro for free and win prizes!

## Coding Challenge #129 - Coding Challenges Coach

DevFeed: [Coding Challenge #129 - Coding Challenges Coach](<https://devfeed.tech/articles/coding-challenge-129-coding-challenges-coach-29205.md>)

Original publisher: [Read original article](<https://codingchallenges.substack.com/p/coding-challenge-129-coding-challenges>)

Author: John Crickett

Published: 2026-07-31T08:02:05Z

Content type: tutorial

Language: en

Sources: [Coding Challenges](<https://devfeed.tech/sources/coding-challenges.md>)

Topics: [Code Challenge](<https://devfeed.tech/topics/code-challenge.md>), [AI Agent](<https://devfeed.tech/topics/ai-agent.md>), [Artificial Intelligence](<https://devfeed.tech/topics/ai.md>), [Google](<https://devfeed.tech/topics/google.md>), [Google Cloud Platform (GCP)](<https://devfeed.tech/topics/google-cloud.md>), [Agent Framework](<https://devfeed.tech/topics/agent-framework.md>), [Security](<https://devfeed.tech/topics/security.md>), [Command-line interface](<https://devfeed.tech/topics/cli.md>)

Tags: [adk](<https://devfeed.tech/tags/adk.md>), [agents](<https://devfeed.tech/tags/agents.md>), [ai-agents](<https://devfeed.tech/tags/ai-agents.md>), [cli](<https://devfeed.tech/tags/cli.md>), [coding](<https://devfeed.tech/tags/coding.md>), [gemini](<https://devfeed.tech/tags/gemini.md>), [google-cloud](<https://devfeed.tech/tags/google-cloud.md>), [how-to](<https://devfeed.tech/tags/how-to.md>), [security](<https://devfeed.tech/tags/security.md>)

### AI overview

Coding Challenge #129 guides developers through building an AI coaching agent for Coding Challenges. The project uses Google's Agent Development Kit and Gemini Enterprise Agent Platform, progressing from a local prototype to a production service on Google Cloud with state management, cost tracking, observability, and security auditing.

### Source excerpt

This challenge is to build your own AI coach for Coding Challenges, learning how to build and deploy production grade AI agents.

## Coding Challenge #128 - Mock Interview Coach

DevFeed: [Coding Challenge #128 - Mock Interview Coach](<https://devfeed.tech/articles/coding-challenge-128-mock-interview-coach-29204.md>)

Original publisher: [Read original article](<https://codingchallenges.substack.com/p/coding-challenge-128-mock-interview>)

Author: John Crickett

Published: 2026-07-25T08:01:05Z

Content type: tutorial

Language: en

Sources: [Coding Challenges](<https://devfeed.tech/sources/coding-challenges.md>)

Topics: [Code Challenge](<https://devfeed.tech/topics/code-challenge.md>), [Artificial Intelligence](<https://devfeed.tech/topics/ai.md>), [web applications](<https://devfeed.tech/topics/web-applications.md>), [API](<https://devfeed.tech/topics/api.md>), [Authentication](<https://devfeed.tech/topics/authentication.md>), [Streaming](<https://devfeed.tech/topics/streaming.md>), [Back end](<https://devfeed.tech/topics/backend.md>), [Front end](<https://devfeed.tech/topics/frontend.md>)

Tags: [ai](<https://devfeed.tech/tags/ai.md>), [api](<https://devfeed.tech/tags/api.md>), [authentication](<https://devfeed.tech/tags/authentication.md>), [backend](<https://devfeed.tech/tags/backend.md>), [coding](<https://devfeed.tech/tags/coding.md>), [frontend](<https://devfeed.tech/tags/frontend.md>), [how-to](<https://devfeed.tech/tags/how-to.md>), [rest-api](<https://devfeed.tech/tags/rest-api.md>), [security](<https://devfeed.tech/tags/security.md>), [streaming](<https://devfeed.tech/tags/streaming.md>), [tokens](<https://devfeed.tech/tags/tokens.md>)

### AI overview

A coding challenge guides developers through building a live AI mock interview coach. The project uses a real-time avatar platform to conduct behavioural interviews, ask follow-up questions, assess responses, and provide feedback from session transcripts.

### Source excerpt

This challenge is to build your own live AI-driven video based mock interview coach.

## Coding Challenge #127 - Tmux

DevFeed: [Coding Challenge #127 - Tmux](<https://devfeed.tech/articles/coding-challenge-127-tmux-29203.md>)

Original publisher: [Read original article](<https://codingchallenges.substack.com/p/coding-challenge-127-tmux>)

Author: John Crickett

Published: 2026-07-18T08:00:26Z

Content type: tutorial

Language: en

Sources: [Coding Challenges](<https://devfeed.tech/sources/coding-challenges.md>)

Topics: [Code Challenge](<https://devfeed.tech/topics/code-challenge.md>), [systems](<https://devfeed.tech/topics/systems.md>), [Programming](<https://devfeed.tech/topics/programming.md>), [Terminal](<https://devfeed.tech/topics/terminal.md>), [Unix](<https://devfeed.tech/topics/unix.md>), [Shell](<https://devfeed.tech/topics/shell.md>)

Tags: [coding](<https://devfeed.tech/tags/coding.md>), [programming](<https://devfeed.tech/tags/programming.md>), [shell](<https://devfeed.tech/tags/shell.md>), [ssh](<https://devfeed.tech/tags/ssh.md>), [systems](<https://devfeed.tech/tags/systems.md>), [terminal](<https://devfeed.tech/tags/terminal.md>), [the-challenge](<https://devfeed.tech/tags/the-challenge.md>), [unix](<https://devfeed.tech/tags/unix.md>)

### AI overview

A coding challenge asks readers to build a simplified version of tmux, a terminal multiplexer. The project covers named sessions, detaching and reattaching, multiple windows, panes, shells, pseudo-terminals, Unix domain sockets, raw terminal modes, and screen rendering.

### Source excerpt

This challenge is to build your own tmux.

## Coding Challenge #126 - Background Removal Tool

DevFeed: [Coding Challenge #126 - Background Removal Tool](<https://devfeed.tech/articles/coding-challenge-126-background-removal-tool-29202.md>)

Original publisher: [Read original article](<https://codingchallenges.substack.com/p/coding-challenge-126-background-removal>)

Author: John Crickett

Published: 2026-07-11T08:01:20Z

Content type: tutorial

Language: en

Sources: [Coding Challenges](<https://devfeed.tech/sources/coding-challenges.md>)

Topics: [Code Challenge](<https://devfeed.tech/topics/code-challenge.md>), [Image processing](<https://devfeed.tech/topics/image-processing.md>), [coding](<https://devfeed.tech/topics/coding.md>)

Tags: [building](<https://devfeed.tech/tags/building.md>), [coding](<https://devfeed.tech/tags/coding.md>), [image-processing](<https://devfeed.tech/tags/image-processing.md>), [images](<https://devfeed.tech/tags/images.md>), [testing](<https://devfeed.tech/tags/testing.md>)

### AI overview

Coding Challenge #126 asks readers to build an on-device image background removal tool. The tool should identify a person in a photograph, preserve the person, make the background transparent, and eventually process individual images or directory trees.

### Source excerpt

This challenge is to build your own background removal tool for images.

## Coding Challenge #125 - Online Diff Viewer

DevFeed: [Coding Challenge #125 - Online Diff Viewer](<https://devfeed.tech/articles/coding-challenge-125-online-diff-viewer-29201.md>)

Original publisher: [Read original article](<https://codingchallenges.substack.com/p/coding-challenge-125-online-diff>)

Author: John Crickett

Published: 2026-07-04T08:01:27Z

Content type: tutorial

Language: en

Sources: [Coding Challenges](<https://devfeed.tech/sources/coding-challenges.md>)

Topics: [Code Challenge](<https://devfeed.tech/topics/code-challenge.md>), [coding](<https://devfeed.tech/topics/coding.md>), [web applications](<https://devfeed.tech/topics/web-applications.md>), [Algorithm](<https://devfeed.tech/topics/algorithm.md>), [Accessibility](<https://devfeed.tech/topics/accessibility.md>), [Syntax Highlighting](<https://devfeed.tech/topics/syntax-highlighting.md>), [navigation](<https://devfeed.tech/topics/navigation.md>), [CSS](<https://devfeed.tech/topics/css.md>), [HTML](<https://devfeed.tech/topics/html.md>), [JavaScript](<https://devfeed.tech/topics/javascript.md>)

Tags: [accessibility](<https://devfeed.tech/tags/accessibility.md>), [algorithm](<https://devfeed.tech/tags/algorithm.md>), [browser](<https://devfeed.tech/tags/browser.md>), [build](<https://devfeed.tech/tags/build.md>), [code](<https://devfeed.tech/tags/code.md>), [coding](<https://devfeed.tech/tags/coding.md>), [css](<https://devfeed.tech/tags/css.md>), [html](<https://devfeed.tech/tags/html.md>), [javascript](<https://devfeed.tech/tags/javascript.md>), [navigation](<https://devfeed.tech/tags/navigation.md>), [syntax-highlighting](<https://devfeed.tech/tags/syntax-highlighting.md>)

### AI overview

Coding Challenge #125 asks readers to build an online diff viewer in the browser. The project compares two text inputs, computes a line-level diff, and presents additions, deletions, and unchanged lines, with planned features including multiple views, syntax highlighting, navigation, export, and accessibility.

### Source excerpt

This challenge is to build your own online diff viewer.

## What should Coding Challenges become next?

DevFeed: [What should Coding Challenges become next?](<https://devfeed.tech/articles/what-should-coding-challenges-become-next-29214.md>)

Original publisher: [Read original article](<https://codingchallenges.substack.com/p/what-should-coding-challenges-become>)

Author: John Crickett

Published: 2026-06-20T08:02:12Z

Content type: opinion

Language: en

Sources: [Coding Challenges](<https://devfeed.tech/sources/coding-challenges.md>)

Topics: [coding](<https://devfeed.tech/topics/coding.md>), [Software Engineering](<https://devfeed.tech/topics/software-engineering.md>), [Artificial Intelligence](<https://devfeed.tech/topics/ai.md>), [Generative AI](<https://devfeed.tech/topics/generative-ai.md>), [code productivity](<https://devfeed.tech/topics/code-productivity.md>)

Tags: [ai](<https://devfeed.tech/tags/ai.md>), [coding](<https://devfeed.tech/tags/coding.md>), [developer-productivity](<https://devfeed.tech/tags/developer-productivity.md>), [newsletter](<https://devfeed.tech/tags/newsletter.md>), [programming](<https://devfeed.tech/tags/programming.md>), [software-engineering](<https://devfeed.tech/tags/software-engineering.md>)

### AI overview

The Coding Challenges newsletter asks readers what would make it worth reading every week. It invites feedback on coding projects, AI and LLMs, software engineering, architecture, testing, system design, and related developer topics, while also offering public comments, private email replies, or unsubscribing.

### Source excerpt

Something needs to change, and I'd like you to help shape it.

## Coding Challenge #124 - Du

DevFeed: [Coding Challenge #124 - Du](<https://devfeed.tech/articles/coding-challenge-124-du-29200.md>)

Original publisher: [Read original article](<https://codingchallenges.substack.com/p/coding-challenge-124-du>)

Author: John Crickett

Published: 2026-06-13T08:01:14Z

Content type: tutorial

Language: en

Sources: [Coding Challenges](<https://devfeed.tech/sources/coding-challenges.md>)

Topics: [Code Challenge](<https://devfeed.tech/topics/code-challenge.md>), [POSIX](<https://devfeed.tech/topics/posix.md>), [Unix](<https://devfeed.tech/topics/unix.md>), [Utility Software](<https://devfeed.tech/topics/utility.md>), [Programming](<https://devfeed.tech/topics/programming.md>)

Tags: [coding](<https://devfeed.tech/tags/coding.md>), [exercise](<https://devfeed.tech/tags/exercise.md>), [filesystem](<https://devfeed.tech/tags/filesystem.md>), [posix](<https://devfeed.tech/tags/posix.md>), [programming](<https://devfeed.tech/tags/programming.md>), [programming-language](<https://devfeed.tech/tags/programming-language.md>), [run](<https://devfeed.tech/tags/run.md>), [unix](<https://devfeed.tech/tags/unix.md>), [utilities](<https://devfeed.tech/tags/utilities.md>)

### AI overview

A coding challenge asks readers to build their own POSIX-compatible du utility. It covers recursively traversing directories, calculating disk usage, handling hard links and symbolic links, and presenting results in multiple formats.

### Source excerpt

This challenge is to build your own du.

## Coding Challenge #123 - Database Driven LLM Wiki

DevFeed: [Coding Challenge #123 - Database Driven LLM Wiki](<https://devfeed.tech/articles/coding-challenge-123-database-driven-llm-wiki-29199.md>)

Original publisher: [Read original article](<https://codingchallenges.substack.com/p/coding-challenge-122-database-driven>)

Author: John Crickett

Published: 2026-06-06T08:01:47Z

Content type: tutorial

Language: en

Sources: [Coding Challenges](<https://devfeed.tech/sources/coding-challenges.md>)

Topics: [Wiki](<https://devfeed.tech/topics/wiki.md>), [LLMs](<https://devfeed.tech/topics/llms.md>), [Database](<https://devfeed.tech/topics/database.md>), [Langgraph](<https://devfeed.tech/topics/langgraph.md>), [LangChain](<https://devfeed.tech/topics/langchain.md>), [Retrieval Augmented Generation (RAG)](<https://devfeed.tech/topics/retrieval-augmented-generation-rag.md>)

Tags: [coding](<https://devfeed.tech/tags/coding.md>), [database](<https://devfeed.tech/tags/database.md>), [knowledge-base](<https://devfeed.tech/tags/knowledge-base.md>), [langchain](<https://devfeed.tech/tags/langchain.md>), [langgraph](<https://devfeed.tech/tags/langgraph.md>), [llms](<https://devfeed.tech/tags/llms.md>), [rag](<https://devfeed.tech/tags/rag.md>)

### AI overview

A coding challenge to build a personal LLM wiki that incrementally maintains a structured Markdown knowledge base from curated sources. The proposed implementation uses Oracle AI Database for vector embeddings and full-text indexes, hybrid search for retrieval, LangGraph for workflows, and LangChain for LLM integration.

### Source excerpt

This challenge is to build your own database powered LLM Wiki.

## Coding Challenge #122 - AI-Powered Contract Review Agent

DevFeed: [Coding Challenge #122 - AI-Powered Contract Review Agent](<https://devfeed.tech/articles/coding-challenge-122-ai-powered-contract-review-agent-29198.md>)

Original publisher: [Read original article](<https://codingchallenges.substack.com/p/coding-challenge-122-ai-powered-contract>)

Author: John Crickett

Published: 2026-05-30T08:01:36Z

Content type: tutorial

Language: en

Sources: [Coding Challenges](<https://devfeed.tech/sources/coding-challenges.md>)

Topics: [Code Challenge](<https://devfeed.tech/topics/code-challenge.md>), [AI Agent](<https://devfeed.tech/topics/ai-agent.md>), [Orchestration](<https://devfeed.tech/topics/orchestration.md>), [Large Language Model](<https://devfeed.tech/topics/llm.md>), [pdf](<https://devfeed.tech/topics/pdf.md>), [human feedback](<https://devfeed.tech/topics/human-feedback.md>), [Concurrency](<https://devfeed.tech/topics/concurrency.md>), [Streaming](<https://devfeed.tech/topics/streaming.md>), [observability](<https://devfeed.tech/topics/observability.md>), [web applications](<https://devfeed.tech/topics/web-applications.md>)

Tags: [agent](<https://devfeed.tech/tags/agent.md>), [ai-agent](<https://devfeed.tech/tags/ai-agent.md>), [coding](<https://devfeed.tech/tags/coding.md>), [concurrency](<https://devfeed.tech/tags/concurrency.md>), [orchestration](<https://devfeed.tech/tags/orchestration.md>), [pdf](<https://devfeed.tech/tags/pdf.md>), [review](<https://devfeed.tech/tags/review.md>), [streaming](<https://devfeed.tech/tags/streaming.md>), [visibility](<https://devfeed.tech/tags/visibility.md>), [web](<https://devfeed.tech/tags/web.md>)

### AI overview

This coding challenge guides readers through building an AI-powered contract review agent with Trigger.dev. The application uploads PDF contracts, extracts and analyzes clauses in parallel with LLMs, pauses for human approval, and streams a final summary to the frontend.

### Source excerpt

This challenge is to build your own AI powered agent to review documents.

## Coding Challenge #121 - Dd

DevFeed: [Coding Challenge #121 - Dd](<https://devfeed.tech/articles/coding-challenge-121-dd-29197.md>)

Original publisher: [Read original article](<https://codingchallenges.substack.com/p/coding-challenge-121-dd>)

Author: John Crickett

Published: 2026-05-23T08:00:59Z

Content type: tutorial

Language: en

Sources: [Coding Challenges](<https://devfeed.tech/sources/coding-challenges.md>)

Topics: [Code Challenge](<https://devfeed.tech/topics/code-challenge.md>), [Unix](<https://devfeed.tech/topics/unix.md>), [coding](<https://devfeed.tech/topics/coding.md>), [Programming](<https://devfeed.tech/topics/programming.md>), [Software](<https://devfeed.tech/topics/software.md>), [Mainframe](<https://devfeed.tech/topics/mainframe.md>)

Tags: [coding](<https://devfeed.tech/tags/coding.md>), [mainframe](<https://devfeed.tech/tags/mainframe.md>), [programming](<https://devfeed.tech/tags/programming.md>), [programming-language](<https://devfeed.tech/tags/programming-language.md>), [testing](<https://devfeed.tech/tags/testing.md>), [unix](<https://devfeed.tech/tags/unix.md>), [usb](<https://devfeed.tech/tags/usb.md>)

### AI overview

A coding challenge asks readers to build their own version of dd, the Unix utility for copying and converting fixed-size data blocks. The article introduces dd's history, operand-based syntax, common uses, and an initial setup step for implementing and testing the tool.

### Source excerpt

This challenge is to build your own dd unix tool.

## Coding Challenge #120 - md5sum

DevFeed: [Coding Challenge #120 - md5sum](<https://devfeed.tech/articles/coding-challenge-120-md5sum-29196.md>)

Original publisher: [Read original article](<https://codingchallenges.substack.com/p/coding-challenge-120-md5sum>)

Author: John Crickett

Published: 2026-05-16T08:16:11Z

Content type: tutorial

Language: en

Sources: [Coding Challenges](<https://devfeed.tech/sources/coding-challenges.md>)

Topics: [Code Challenge](<https://devfeed.tech/topics/code-challenge.md>), [Command-line interface](<https://devfeed.tech/topics/cli.md>), [hashing](<https://devfeed.tech/topics/hashing.md>), [integrity](<https://devfeed.tech/topics/integrity.md>), [Programming](<https://devfeed.tech/topics/programming.md>), [Security](<https://devfeed.tech/topics/security.md>)

Tags: [algorithm](<https://devfeed.tech/tags/algorithm.md>), [code](<https://devfeed.tech/tags/code.md>), [coding](<https://devfeed.tech/tags/coding.md>), [command-line](<https://devfeed.tech/tags/command-line.md>), [integrity](<https://devfeed.tech/tags/integrity.md>), [security](<https://devfeed.tech/tags/security.md>), [support](<https://devfeed.tech/tags/support.md>)

### AI overview

A coding challenge guides readers through building an md5sum command-line utility. One track uses a standard or third-party library for hashing, while another implements MD5 from scratch using RFC 1321, covering file handling, check mode, message padding, the Merkle-Damgård construction, and the compression function.

### Source excerpt

This challenge is to build your own md5sum.

## Coding Challenge #119 - AI Pong Player

DevFeed: [Coding Challenge #119 - AI Pong Player](<https://devfeed.tech/articles/coding-challenge-119-ai-pong-player-29195.md>)

Original publisher: [Read original article](<https://codingchallenges.substack.com/p/coding-challenge-119-ai-pong-player>)

Author: John Crickett

Published: 2026-05-09T08:01:53Z

Content type: tutorial

Language: en

Sources: [Coding Challenges](<https://devfeed.tech/sources/coding-challenges.md>)

Topics: [Code Challenge](<https://devfeed.tech/topics/code-challenge.md>), [Reinforcement learning](<https://devfeed.tech/topics/reinforcement-learning.md>), [coding](<https://devfeed.tech/topics/coding.md>), [Deep neural networks](<https://devfeed.tech/topics/deep-neural-networks.md>), [NumPy](<https://devfeed.tech/topics/numpy.md>)

Tags: [ai](<https://devfeed.tech/tags/ai.md>), [coding](<https://devfeed.tech/tags/coding.md>), [games](<https://devfeed.tech/tags/games.md>), [neural-networks](<https://devfeed.tech/tags/neural-networks.md>), [python](<https://devfeed.tech/tags/python.md>), [reinforcement-learning](<https://devfeed.tech/tags/reinforcement-learning.md>)

### AI overview

A coding challenge guides readers through building a reinforcement learning agent that learns to play Atari Pong from raw screen pixels. It introduces policy gradients, the REINFORCE algorithm, returns, stochastic policies, and variance reduction, with Python and NumPy as prerequisites.

### Source excerpt

This challenge is to build your own AI pong player with reinforcement learning.