# Server-sent events (SSE)

A web technology that enables servers to push event data to web pages over HTTP through the EventSource interface.

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## Diagnosing a 28,232-Connection SSE Limit in a Go Leaderboard

DevFeed: [Diagnosing a 28,232-Connection SSE Limit in a Go Leaderboard](<https://devfeed.tech/articles/breaking-the-28k-sse-connection-limit-and-scaling-toward-1m-39412.md>)

Original publisher: [Read original article](<https://blog.pranshu-raj.in/posts/scaling-sse-1m-connections/>)

Author: Pranshu Raj

Published: 2026-07-23T00:00:00Z

Content type: tutorial

Language: en

Sources: [Pranshu Raj - blog on backend systems, performance and sidequests](<https://devfeed.tech/sources/pranshu-raj-blog-on-backend-systems-performance-and-sidequests.md>)

Topics: [Server-sent events (SSE)](<https://devfeed.tech/topics/server-sent-events-sse.md>), [Go Language](<https://devfeed.tech/topics/go-language.md>), [Docker Compose](<https://devfeed.tech/topics/docker-compose.md>), [Redis](<https://devfeed.tech/topics/redis.md>), [Grafana](<https://devfeed.tech/topics/grafana.md>), [Prometheus](<https://devfeed.tech/topics/prometheus.md>)

Tags: [docker-compose](<https://devfeed.tech/tags/docker-compose.md>), [go](<https://devfeed.tech/tags/go.md>), [grafana](<https://devfeed.tech/tags/grafana.md>), [prometheus](<https://devfeed.tech/tags/prometheus.md>), [redis](<https://devfeed.tech/tags/redis.md>), [sse](<https://devfeed.tech/tags/sse.md>)

### AI overview

A tutorial on testing and diagnosing the SSE connection limit of a Go leaderboard service. It describes the service architecture, Docker Compose deployment, and monitoring with Prometheus and Grafana.

### Source excerpt

Why my Go leaderboard's capped at exactly 28,232 SSE connections, how Docker networking got me to 150k, and the path toward millions.

## Broadcasting to 28K SSE Clients (and learning about Go channels)

DevFeed: [Broadcasting to 28K SSE Clients (and learning about Go channels)](<https://devfeed.tech/articles/broadcasting-to-28k-sse-clients-and-learning-about-go-channels-39405.md>)

Original publisher: [Read original article](<https://blog.pranshu-raj.in/posts/implementing-correct-fanout/>)

Author: Pranshu Raj

Published: 2026-07-23T00:00:00Z

Content type: tutorial

Language: en

Sources: [Pranshu Raj - blog on backend systems, performance and sidequests](<https://devfeed.tech/sources/pranshu-raj-blog-on-backend-systems-performance-and-sidequests.md>)

Topics: [Go Language](<https://devfeed.tech/topics/go-language.md>), [Server-sent events (SSE)](<https://devfeed.tech/topics/server-sent-events-sse.md>), [Concurrency](<https://devfeed.tech/topics/concurrency.md>), [backpressure](<https://devfeed.tech/topics/backpressure.md>), [real-time](<https://devfeed.tech/topics/real-time.md>), [observability](<https://devfeed.tech/topics/observability.md>), [Redis](<https://devfeed.tech/topics/redis.md>), [Grafana](<https://devfeed.tech/topics/grafana.md>), [Prometheus](<https://devfeed.tech/topics/prometheus.md>)

Tags: [architecture](<https://devfeed.tech/tags/architecture.md>), [backpressure](<https://devfeed.tech/tags/backpressure.md>), [concurrency](<https://devfeed.tech/tags/concurrency.md>), [go](<https://devfeed.tech/tags/go.md>), [grafana](<https://devfeed.tech/tags/grafana.md>), [observability](<https://devfeed.tech/tags/observability.md>), [prometheus](<https://devfeed.tech/tags/prometheus.md>), [real-time](<https://devfeed.tech/tags/real-time.md>), [redis](<https://devfeed.tech/tags/redis.md>), [sse](<https://devfeed.tech/tags/sse.md>)

### AI overview

The article describes building a real-time leaderboard in Go that reached 28,232 concurrent SSE connections before exposing a broken broadcast design. It explains the fix using centralized polling, deduplication, fan-out, backpressure handling, and observability with Prometheus and Grafana.

### Source excerpt

A post on progressively getting my server to 28k SSE connections, finding a bug in my implementation of fan out using Go channels and the resulting mental model update.

## Closing SSE Connections: A Browser Compatibility Deep Dive

DevFeed: [Closing SSE Connections: A Browser Compatibility Deep Dive](<https://devfeed.tech/articles/closing-sse-connections-a-browser-compatibility-deep-dive-37520.md>)

Original publisher: [Read original article](<https://blog.apartment304.com/sse-close-connection/>)

Author: James Heller

Published: 2025-11-20T19:00:00Z

Content type: tutorial

Language: en

Sources: [Apartment 304](<https://devfeed.tech/sources/apartment-304.md>)

Topics: [Server-sent events (SSE)](<https://devfeed.tech/topics/server-sent-events-sse.md>), [JavaScript](<https://devfeed.tech/topics/javascript.md>), [htmx](<https://devfeed.tech/topics/htmx.md>), [HTTP](<https://devfeed.tech/topics/http.md>), [Firefox](<https://devfeed.tech/topics/firefox.md>), [Chrome](<https://devfeed.tech/topics/chrome.md>)

Tags: [ajax](<https://devfeed.tech/tags/ajax.md>), [apartment-304](<https://devfeed.tech/tags/apartment-304.md>), [browser](<https://devfeed.tech/tags/browser.md>), [compatibility](<https://devfeed.tech/tags/compatibility.md>), [custom-software-solutions](<https://devfeed.tech/tags/custom-software-solutions.md>), [devops](<https://devfeed.tech/tags/devops.md>), [devops-engineer](<https://devfeed.tech/tags/devops-engineer.md>), [htmx](<https://devfeed.tech/tags/htmx.md>), [http](<https://devfeed.tech/tags/http.md>), [implementation](<https://devfeed.tech/tags/implementation.md>), [issue](<https://devfeed.tech/tags/issue.md>), [javascript](<https://devfeed.tech/tags/javascript.md>), [multiplayer](<https://devfeed.tech/tags/multiplayer.md>), [software-architecture](<https://devfeed.tech/tags/software-architecture.md>), [software-development](<https://devfeed.tech/tags/software-development.md>), [software-engineer](<https://devfeed.tech/tags/software-engineer.md>), [sse](<https://devfeed.tech/tags/sse.md>)

### AI overview

This tutorial explains how Server-Sent Events connections can remain open inconsistently across browsers when users navigate away. Using the multiplayer mystery game Whodunit with HTMX as an example, it describes SSE connection tracking and a client-side JavaScript approach for robust cleanup.

### Source excerpt

When browsers leave connections dangling, your app can get stuck waiting for users who are already gone. Let's solve the mystery of closing SSE connections.

## Building a scalable real time leaderboard

DevFeed: [Building a scalable real time leaderboard](<https://devfeed.tech/articles/building-a-scalable-real-time-leaderboard-39408.md>)

Original publisher: [Read original article](<https://blog.pranshu-raj.in/posts/leaderboard/>)

Author: Pranshu Raj

Published: 2025-11-14T17:12:32Z

Content type: tutorial

Language: en

Sources: [Pranshu Raj - blog on backend systems, performance and sidequests](<https://devfeed.tech/sources/pranshu-raj-blog-on-backend-systems-performance-and-sidequests.md>)

Topics: [real-time](<https://devfeed.tech/topics/real-time.md>), [Go Language](<https://devfeed.tech/topics/go-language.md>), [Redis](<https://devfeed.tech/topics/redis.md>), [Server-sent events (SSE)](<https://devfeed.tech/topics/server-sent-events-sse.md>), [Concurrency](<https://devfeed.tech/topics/concurrency.md>), [Latency](<https://devfeed.tech/topics/latency.md>), [Grafana](<https://devfeed.tech/topics/grafana.md>), [Prometheus](<https://devfeed.tech/topics/prometheus.md>)

Tags: [building](<https://devfeed.tech/tags/building.md>), [concurrency](<https://devfeed.tech/tags/concurrency.md>), [go](<https://devfeed.tech/tags/go.md>), [grafana](<https://devfeed.tech/tags/grafana.md>), [latency](<https://devfeed.tech/tags/latency.md>), [prometheus](<https://devfeed.tech/tags/prometheus.md>), [real-time](<https://devfeed.tech/tags/real-time.md>), [redis](<https://devfeed.tech/tags/redis.md>)

### AI overview

A developer describes building a real-time tournament leaderboard with Go, Redis Sorted Sets, and Server-Sent Events. The article covers its architecture, concurrency and latency requirements, live client updates, and experiments with Prometheus and Grafana observability.

### Source excerpt

Describing my journey of building the leaderboard, what I learnt, what issues I faced, and some design decisions (which will be elaborated on later).

## Scaling Server Sent Events - Intro to SSE and scaling guide

DevFeed: [Scaling Server Sent Events - Intro to SSE and scaling guide](<https://devfeed.tech/articles/scaling-server-sent-events-intro-to-sse-and-scaling-guide-39403.md>)

Original publisher: [Read original article](<https://blog.pranshu-raj.in/posts/exploring-sse/>)

Author: Pranshu Raj

Published: 2025-06-29T07:01:27Z

Content type: tutorial

Language: en

Sources: [Pranshu Raj - blog on backend systems, performance and sidequests](<https://devfeed.tech/sources/pranshu-raj-blog-on-backend-systems-performance-and-sidequests.md>)

Topics: [Server-sent events (SSE)](<https://devfeed.tech/topics/server-sent-events-sse.md>), [scaling](<https://devfeed.tech/topics/scaling.md>), [HTTP](<https://devfeed.tech/topics/http.md>), [WebSocket](<https://devfeed.tech/topics/websocket.md>)

Tags: [guide](<https://devfeed.tech/tags/guide.md>), [scaling](<https://devfeed.tech/tags/scaling.md>), [sse](<https://devfeed.tech/tags/sse.md>)

### AI overview

A tutorial on Server-Sent Events (SSE), covering its HTTP-based server-to-client update model, event-stream format, browser EventSource support, and considerations for horizontal scaling and state handling.

### Source excerpt

Understanding SSE and it's use cases, advantages over other realtime protocols, how to deploy it at scale.