--- title: Chameleon templates, modernized: chameleon-rs | daily.dev description: chameleon-rs is a Rust reimplementation of the Chameleon templating language for Python web apps. It runs existing Chameleon templates unchanged with... canonical: https://daily.dev/posts/chameleon-templates-modernized-chameleon-rs-mavwareqf twitter:card: summary_large_image twitter:site: @dailydotdev og:type: website og:site_name: daily.dev og:title: Chameleon templates, modernized: chameleon-rs | daily.dev og:description: chameleon-rs is a Rust reimplementation of the Chameleon templating language for Python web apps. It runs existing Chameleon templates unchanged with... og:url: https://daily.dev/posts/chameleon-templates-modernized-chameleon-rs-mavwareqf og:image: https://api.daily.dev/og/posts/MAVwAReQf.png og:image:alt: Chameleon templates, modernized: chameleon-rs og:image:width: 1200 og:image:height: 630 og:locale: en --- > ## Documentation Index > Fetch the complete documentation index at: https://daily.dev/llms.txt > Use this file to discover all available pages before exploring further. # Chameleon templates, modernized: chameleon-rs **[Planet Python](https://daily.dev/sources/planetpython)** · 5 min read · 2 upvotes · 0 comments ## Summary chameleon-rs is a Rust reimplementation of the Chameleon templating language for Python web apps. It runs existing Chameleon templates unchanged with byte-identical output, several times faster. In one web app, switching cut median response times by roughly 20% across the whole site, not just template rendering. It adds async rendering via render_async(), built-in partials, a Markdown expression (roughly 26x faster than mistune with the same extensions), and thread-safe free-threaded Python support. Migration takes one line with compat.install(), or you can switch imports directly. A shadow mode lets you run both engines side by side on real traffic before fully switching. ## Full article daily.dev links to this article rather than hosting it. Read it at the original source: ## Questions this post answers ### How do I switch my Flask or FastAPI app from Chameleon to chameleon-rs without rewriting templates? Add 'import chameleon_rs.compat' and call 'chameleon_rs.compat.install()' at the very top of your app's entry point, before anything imports Chameleon. This installs a compatibility alias so existing Chameleon templates and code run unchanged with byte-identical output. Alternatively, switch imports directly from chameleon to chameleon_rs, and from chameleon_partials/chameleon_flask to chameleon_rs.partials/chameleon_rs.flask. _Track emerging drop-in replacements like this on daily.dev before committing a production template stack._ ### Does Chameleon templates support Python 3.14 free-threaded mode? The original Chameleon package does not; its repository shows support only up to Python 3.13 and a failing build. chameleon-rs, a Rust reimplementation, was built specifically to add thread-safe rendering without the GIL, targeting free-threaded Python 3.14 and ongoing 3.15 development, after extensive profiling to minimize shared data and locking. _Developers planning a free-threaded Python migration can follow templating compatibility updates on daily.dev._ ### How much faster is Markdown rendering in chameleon-rs compared to mistune? Markdown conversion inside chameleon-rs templates runs roughly 26 times faster than mistune with the same extensions. It uses the comrak Markdown converter built into chameleon-rs in Rust, so no separate Markdown package needs installing, and it's enabled via configure(markdown=True) with a markdown: expression in templates. _Compare templating and Markdown rendering benchmarks on daily.dev before picking a stack for performance-sensitive apps._ ## Similar posts on daily.dev - [What I learned using Claude Sonnet to migrate Python to Rust](https://daily.dev/posts/what-i-learned-using-claude-sonnet-to-migrate-python-to-rust-wtchq1s8n) · InfoWorld · 10 upvotes · 1 comments - [As If](https://daily.dev/posts/as-if-v1hq1kbgo) · RUBYLAND · 0 upvotes · 0 comments --- Tags: [#python](https://daily.dev/tags/python), [#rust](https://daily.dev/tags/rust) [View this post on daily.dev](https://daily.dev/posts/chameleon-templates-modernized-chameleon-rs-mavwareqf) ```json {"@context":"https://schema.org","@graph":[{"@type":"Organization","@id":"https://daily.dev/#organization","name":"daily.dev","url":"https://daily.dev","logo":{"@type":"ImageObject","url":"https://daily.dev/apple-touch-icon.png","width":180,"height":180},"sameAs":["https://twitter.com/dailydotdev","https://github.com/dailydotdev","https://www.linkedin.com/company/daily-dev-ltd"]},{"@type":"WebSite","@id":"https://daily.dev/#website","url":"https://daily.dev","name":"daily.dev","publisher":{"@id":"https://daily.dev/#organization"},"potentialAction":{"@type":"SearchAction","target":{"@type":"EntryPoint","urlTemplate":"https://daily.dev/search?q={search_term_string}"},"query-input":"required name=search_term_string"}}]} {"@context":"https://schema.org","@type":"TechArticle","headline":"Chameleon templates, modernized: chameleon-rs","url":"https://daily.dev/posts/chameleon-templates-modernized-chameleon-rs-mavwareqf","mainEntityOfPage":{"@type":"WebPage","@id":"https://daily.dev/posts/chameleon-templates-modernized-chameleon-rs-mavwareqf"},"datePublished":"2026-10-28T04:53:58.690Z","dateModified":"2026-10-28T05:44:54.445Z","description":"chameleon-rs is a Rust reimplementation of the Chameleon templating language for Python web apps. 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