# Matching JSON and whitespace characters efficiently on ARM processors

DevFeed: [Matching JSON and whitespace characters efficiently on ARM processors](<https://devfeed.tech/articles/the-fastest-way-to-match-characters-on-arm-processors-29401.md>)

Original publisher: [Read original article](<https://lemire.me/blog/2026/04/19/the-fastest-way-to-match-characters-on-arm-processors/>)

Author: Daniel Lemire

Published: 2026-04-19T20:41:04Z

Content type: article

Language: en

Sources: [Daniel Lemire](<https://devfeed.tech/sources/daniel-lemire.md>)

Topics: [Arm](<https://devfeed.tech/topics/arm.md>), [JSON](<https://devfeed.tech/topics/json.md>), [Parsing](<https://devfeed.tech/topics/parsing.md>)

Tags: [amd](<https://devfeed.tech/tags/amd.md>), [architecture](<https://devfeed.tech/tags/architecture.md>), [arm](<https://devfeed.tech/tags/arm.md>), [ascii](<https://devfeed.tech/tags/ascii.md>), [avx](<https://devfeed.tech/tags/avx.md>), [intel](<https://devfeed.tech/tags/intel.md>), [json](<https://devfeed.tech/tags/json.md>), [parsing](<https://devfeed.tech/tags/parsing.md>), [processors](<https://devfeed.tech/tags/processors.md>)

## AI overview

The article examines vectorized classification for matching ASCII whitespace and structural JSON characters. It describes a branch-free NEON approach and discusses newer ARM Scalable Vector Extension instructions as an alternative on recent ARM processors.

## Source excerpt

Consider the following problem. Given a string, you must match all of the ASCII white-space characters (\t, \n, \r, and the space) and some characters important in JSON (:, ,, [, ], {, }). JSON is a text-based data format used for web services. A toy JSON document looks as follows. { "name": "Alice", "age": ... Continue reading The fastest way to match characters on ARM processors?