# Fastify changelog

> A fast and low-overhead web framework for Node.js.

- Vendor: Fastify
- Category: Frameworks & Libraries
- Official site: https://fastify.dev
- Tracked by: What's New (https://whatsnew.fyi/product/fastify)
- Harvested from: GitHub (fastify/fastify)
- Entries below: 10 (newest first)

What's New is an index, not a publisher: every entry below links to the vendor's own release notes, which are the authoritative source. Entries are labelled where they are hand-curated sample data, pre-releases, or drawn from a secondary source such as a developer blog.

Reuse: the summaries, labels and curation here are © What's New. Quote freely with attribution and a link back; wholesale republication of the corpus is not permitted — terms: https://whatsnew.fyi/terms. The vendors' own release notes remain their publishers'.

## Releases

### v5.11.3

- Date: 2026-08-08
- Version: v5.11.3
- Original notes: https://github.com/fastify/fastify/releases/tag/v5.11.3
- Permalink: https://whatsnew.fyi/product/fastify/releases/v5.11.3

- **fixed** — Clear trailer state when removing all trailers
- **fixed** — Pass null instead of undefined to requestCompleted on success
- **fixed** — Recognize constructor-assigned built-in properties as decorator
- **fixed** — Reset lastIndex before testing global/sticky content-type RegExp parsers

##### What's Changed
* fix: clear trailer state when removing all trailers by @Ram-blip in https://github.com/fastify/fastify/pull/6845
* docs: document percent-decoded route params as untrusted input by @mcollina in https://github.com/fastify/fastify/pull/6903
* docs(errors): document what the default error handler sends by @basteez in https://github.com/fastify/fastify/pull/6894
* docs(readme): fix grammar and cjs capitalization by @minirang in https://github.com/fastify/fastify/pull/6899
* fix: pass null instead of undefined to requestCompleted on success by @lazerg in https://github.com/fastify/fastify/pull/6837
* docs(encapsulation): clarify nested plugin scopes by @jean-michelet in https://github.com/fastify/fastify/pull/6893
* chore: Bump fastify/workflows/.github/workflows/lock-threads.yml from 6.0.0 to 7.0.0 by @dependabot[bot] in https://github.com/fastify/fastify/pull/6916
* chore: Bump fastify/workflows/.github/workflows/nested-quality.yml from 6.0.0 to 7.0.0 by @dependabot[bot] in https://github.com/fastify/fastify/pull/6917
* fix: recognize constructor-assigned built-in properties as decorator … by @aquie00t in https://github.com/fastify/fastify/pull/6892
* fix: reset lastIndex before testing global/sticky content-type RegExp parsers by @zelinewang in https://github.com/fastify/fastify/pull/6846

##### New Contributors
* @minirang made their first contribution in https://github.com/fastify/fastify/pull/6899
* @lazerg made their first contribution in https://github.com/fastify/fastify/pull/6837
* @zelinewang made their first contribution in https://github.com/fastify/fastify/pull/6846

**Full Changelog**: https://github.com/fastify/fastify/compare/v5.11.2...v5.11.3

### v5.11.2

- Date: 2026-08-03
- Version: v5.11.2
- Original notes: https://github.com/fastify/fastify/releases/tag/v5.11.2
- Permalink: https://whatsnew.fyi/product/fastify/releases/v5.11.2

- **fixed** — fix fastify version in fastify.js

##### What's Changed

- fix fastify version in `fastify.js`

**Full Changelog**: https://github.com/fastify/fastify/compare/v5.11.1...v5.11.2

### v5.11.1

- Date: 2026-08-03
- Version: v5.11.1
- Original notes: https://github.com/fastify/fastify/releases/tag/v5.11.1
- Permalink: https://whatsnew.fyi/product/fastify/releases/v5.11.1

- **fixed** — Add http method override warning
- **fixed** — Allow explicit http2: false in server options
- **fixed** — Do not force close in-flight connections when forceCloseConnections is 'idle'

##### What's Changed
* fix: add http method override warning by @jean-michelet in https://github.com/fastify/fastify/pull/6879
* fix(types): allow explicit http2: false in server options by @Tony133 in https://github.com/fastify/fastify/pull/6888
* docs: clarify what attachValidation exposes on request.validationError by @basteez in https://github.com/fastify/fastify/pull/6891
* fix: do not force close in-flight connections when forceCloseConnections is 'idle' by @aquie00t in https://github.com/fastify/fastify/pull/6889

##### New Contributors
* @basteez made their first contribution in https://github.com/fastify/fastify/pull/6891

**Full Changelog**: https://github.com/fastify/fastify/compare/v5.11.0...v5.11.1

### v5.11.0

- Date: 2026-07-30
- Version: v5.11.0
- Original notes: https://github.com/fastify/fastify/releases/tag/v5.11.0
- Permalink: https://whatsnew.fyi/product/fastify/releases/v5.11.0

- **fixed** — Normalize method in findRoute
- **added** — RFC 10008 HTTP query method support
- **changed** — Reuse cached content types for response serialization
- **fixed** — Correctly update falsy values from validator
- **fixed** — Uncatchable throws in writeHead when using async hook
- **fixed** — Honor quoted-string in Content-Type parameter values

##### What's Changed
* chore: Bump markdownlint-cli2 from 0.22.1 to 0.23.0 by @dependabot[bot] in https://github.com/fastify/fastify/pull/6839
* fix: normalize method in findRoute by @Ram-blip in https://github.com/fastify/fastify/pull/6838
* docs: fix incorrect description for validateInput in Request.md by @thePranav-kpk in https://github.com/fastify/fastify/pull/6823
* feat: rfc10008 http query method by @climba03003 in https://github.com/fastify/fastify/pull/6832
* perf: reuse cached content types for response serialization by @gurgunday in https://github.com/fastify/fastify/pull/6854
* chore(sponsor): add n-ix by @Eomm in https://github.com/fastify/fastify/pull/6852
* ci: pin actions to commit-hash by @Fdawgs in https://github.com/fastify/fastify/pull/6853
* ci(dependabot): temporarily ignore typescript updates by @Tony133 in https://github.com/fastify/fastify/pull/6869
* style(types): enforce max line length by @jean-michelet in https://github.com/fastify/fastify/pull/6864
* docs(ecosystem): update fastify-prisma repo URL by @zrosenbauer in https://github.com/fastify/fastify/pull/6724
* docs(getting-started): align import with exported routes by @Solaris-star in https://github.com/fastify/fastify/pull/6859
* docs(server): fix contradictory requestIdHeader default by @sobol-sudo in https://github.com/fastify/fastify/pull/6872
* fix(validation): correctly update falsy values from validator by @jackjin1997 in https://github.com/fastify/fastify/pull/6483
* docs: specific warning suppression by @jean-michelet in https://github.com/fastify/fastify/pull/6871
* ci(links-check): pin linkinator server root to the workspace by @aquie00t in https://github.com/fastify/fastify/pull/6877
* docs: update TypeScript docs to reference Fastify 5.x by @Sasireddy001 in https://github.com/fastify/fastify/pull/6880
* docs: use async trailer handlers in Reply examples by @Ram-blip in https://github.com/fastify/fastify/pull/6856
* docs: fix logController migration example and links by @aquie00t in https://github.com/fastify/fastify/pull/6876
* fix: uncatchable throws in writeHead when using async hook by @climba03003 in https://github.com/fastify/fastify/pull/6881
* fix: honor quoted-string in `Content-Type` parameter values by @aquie00t in https://github.com/fastify/fastify/pull/6865
* chore(.npmrc): add min-release-age by @Fdawgs in https://github.com/fastify/fastify/pull/6873
* chore: Bump actions/setup-node from 6.4.0 to 7.0.0 by @dependabot[bot] in https://github.com/fastify/fastify/pull/6866
* chore: Bump actions/labeler from 6.2.0 to 7.0.0 by @dependabot[bot] in https://github.com/fastify/fastify/pull/6867

##### New Contributors
* @Ram-blip made their first contribution in https://github.com/fastify/fastify/pull/6838
* @Solaris-star made their first contribution in https://github.com/fastify/fastify/pull/6859
* @sobol-sudo made their first contribution in https://github.com/fastify/fastify/pull/6872
* @jackjin1997 made their first contribution in https://github.com/fastify/fastify/pull/6483
* @Sasireddy001 made their first contribution in https://github.com/fastify/fastify/pull/6880

**Full Changelog**: https://github.com/fastify/fastify/compare/v5.10.0...v5.11.0

### v5.10.0

- Date: 2026-07-05
- Version: v5.10.0
- Original notes: https://github.com/fastify/fastify/releases/tag/v5.10.0
- Permalink: https://whatsnew.fyi/product/fastify/releases/v5.10.0

- **added** — Introduce log controller layer
- **fixed** — Clear socket._meta on reply.hijack() when onTimeout is registered
- **fixed** — Use ContentType to detect json and charset in reply.send
- **fixed** — Derive request.port from request.host
- **changed** — Reduce per-request overhead in the request lifecycle

##### What's Changed
* docs(type-providers): clarify as const usage by @smith558 in https://github.com/fastify/fastify/pull/6772
* docs: fix broken and redirected links by @Eomm in https://github.com/fastify/fastify/pull/6817
* docs: remove marko from @fastify/view engines (support dropped) by @EduardF1 in https://github.com/fastify/fastify/pull/6821
* fix: clear socket._meta on reply.hijack() when onTimeout is registered by @nerkoux in https://github.com/fastify/fastify/pull/6810
* docs: fix duplicate routeOptions entries in Request.md example by @thePranav-kpk in https://github.com/fastify/fastify/pull/6824
* chore: Bump @types/node from 25.9.4 to 26.0.1 in the dev-dependencies-typescript group by @dependabot[bot] in https://github.com/fastify/fastify/pull/6829
* docs(ecosystem): add @stitchapi/fastify to Community plugins by @rejifald in https://github.com/fastify/fastify/pull/6820
* feat: introduce log controller layer by @Eomm in https://github.com/fastify/fastify/pull/6580
* fix: use ContentType to detect `json` and `charset` in reply.send by @climba03003 in https://github.com/fastify/fastify/pull/6830
* docs: fix incorrect defaults and code examples in Server.md by @Adit-Jain-srm in https://github.com/fastify/fastify/pull/6805
* docs: fix incorrect hook count in Hooks.md by @thePranav-kpk in https://github.com/fastify/fastify/pull/6825
* chore: Bump fast-json-stringify from 6.4.0 to 7.0.0 in the dependencies group across 1 directory by @dependabot[bot] in https://github.com/fastify/fastify/pull/6800
* perf: reduce per-request overhead in the request lifecycle by @mcollina in https://github.com/fastify/fastify/pull/6831
* fix: derive request.port from request.host by @mcollina in https://github.com/fastify/fastify/pull/6680
* docs: update Logging.md with per-route log level info by @asppsa in https://github.com/fastify/fastify/pull/6627
* docs(type-providers): update import for article consistency by @smith558 in https://github.com/fastify/fastify/pull/6771

##### New Contributors
* @EduardF1 made their first contribution in https://github.com/fastify/fastify/pull/6821
* @thePranav-kpk made their first contribution in https://github.com/fastify/fastify/pull/6824
* @rejifald made their first contribution in https://github.com/fastify/fastify/pull/6820
* @Adit-Jain-srm made their first contribution in https://github.com/fastify/fastify/pull/6805
* @asppsa made their first contribution in https://github.com/fastify/fastify/pull/6627

**Full Changelog**: https://github.com/fastify/fastify/compare/v5.9.0...v5.10.0

### v5.9.0

- Date: 2026-06-28
- Version: v5.9.0
- Original notes: https://github.com/fastify/fastify/releases/tag/v5.9.0
- Permalink: https://whatsnew.fyi/product/fastify/releases/v5.9.0

- **added** — Add request.mediaType property
- **added** — Add support of onMaxParamLength hook
- **fixed** — Prevent duplicate res.end in sendTrailer with sync callbacks
- **fixed** — Avoid duplicate closeIdleConnections call on native servers
- **fixed** — Ensure error.code is present on routing errors
- **fixed** — Correct isCustomSerializerCompiler flag check
- **fixed** — Validate invalid route logLevel at registration
- **fixed** — Use ContentType parser for response schema lookup
- **fixed** — Allow request.getValidationFunction() to return undefined
- **fixed** — Do not trust forwarded host/proto when socket is missing
- **fixed** — Enable diagnostics tracking for async error handlers
- **fixed** — Ignore duplicate trailer completions
- **fixed** — Include hint and docs URL in FSTWRN004 warning message
- **fixed** — Chunk large HTTP/2 buffer replies
- **fixed** — Replace AssertionError with FST_ERR_PLUGIN_DEPENDENCY_NOT_REGISTERED in checkDependencies
- **changed** — Defer ContentType parsing in getSchemaSerializer until needed
- **changed** — Cache parsed ContentType objects in ContentTypeParser
- **changed** — Add typeof guard before toString.call in send and onSendEnd
- **changed** — Replace find with some in hasKey for correct boolean semantics

##### What's Changed
* feat: add request.mediaType by @climba03003 in https://github.com/fastify/fastify/pull/6653
* docs: remove deprecated leveldb plugin and update ecosystem by @Tony133 in https://github.com/fastify/fastify/pull/6661
* chore(sponsor): add bestforandroid by @Eomm in https://github.com/fastify/fastify/pull/6659
* ci: drop Node.js 20 from yarn matrix in package-manager-ci.yml by @Tony133 in https://github.com/fastify/fastify/pull/6662
* fix: prevent duplicate res.end in sendTrailer with sync callbacks by @climba03003 in https://github.com/fastify/fastify/pull/6676
* fix: avoid duplicate closeIdleConnections call on native servers by @trivikr in https://github.com/fastify/fastify/pull/6669
* fix: error.code not present on some routing errors by @mcollina in https://github.com/fastify/fastify/pull/6678
* fix: correct isCustomSerializerCompiler flag check by @eddieran in https://github.com/fastify/fastify/pull/6657
* fix: validate invalid route logLevel at registration by @maxpetrusenko in https://github.com/fastify/fastify/pull/6523
* docs: update contribution rules by @Tony133 in https://github.com/fastify/fastify/pull/6670
* fix: use ContentType parser for response schema lookup by @UlisesGascon in https://github.com/fastify/fastify/pull/6685
* ci(ci): use shared quality workflow by @Fdawgs in https://github.com/fastify/fastify/pull/6688
* fix(types): allow request.getValidationFunction() to return undefined by @trivikr in https://github.com/fastify/fastify/pull/6665
* fix: do not trust forwarded host/proto when socket is missing by @mcollina in https://github.com/fastify/fastify/pull/6684
* perf: defer ContentType parsing in getSchemaSerializer until needed by @aquie00t in https://github.com/fastify/fastify/pull/6692
* perf: cache parsed ContentType objects in ContentTypeParser by @aquie00t in https://github.com/fastify/fastify/pull/6694
* perf: add typeof guard before toString.call in send and onSendEnd by @aquie00t in https://github.com/fastify/fastify/pull/6693
* chore: Bump pnpm/action-setup from 5.0.0 to 6.0.4 by @dependabot[bot] in https://github.com/fastify/fastify/pull/6704
* chore: Bump actions/github-script from 8 to 9 by @dependabot[bot] in https://github.com/fastify/fastify/pull/6705
* chore: Bump JustinBeckwith/linkinator-action from 2.4.0 to 2.4.2 by @dependabot[bot] in https://github.com/fastify/fastify/pull/6706
* docs: correct return503OnClosing comment in route.js by @mcollina in https://github.com/fastify/fastify/pull/6712
* fix: enable diagnostics tracking for async error handlers by @irzix in https://github.com/fastify/fastify/pull/6458
* fix: ignore duplicate trailer completions by @mcollina in https://github.com/fastify/fastify/pull/6714
* feat: add support of onMaxParamLength by @climba03003 in https://github.com/fastify/fastify/pull/6716
* chore: introduce TSTyche for type testing by @mrazauskas in https://github.com/fastify/fastify/pull/6532
* docs(reference): grammar and readability fixes by @Fdawgs in https://github.com/fastify/fastify/pull/6710
* chore: update depedabot setting by @climba03003 in https://github.com/fastify/fastify/pull/6715
* fix: include hint and docs URL in FSTWRN004 warning message by @aquie00t in https://github.com/fastify/fastify/pull/6723
* ci(ci): do not pass secrets to reusable workflow by @Fdawgs in https://github.com/fastify/fastify/pull/6744
* docs: add fastify-intlayer to ecosystem documentation by @aymericzip in https://github.com/fastify/fastify/pull/6594
* chore: Bump concurrently from 9.2.1 to 10.0.0 by @dependabot[bot] in https://github.com/fastify/fastify/pull/6752
* docs(Errors): fix incorrect usage of root fastify inside plugin scope by @Rpaudel379 in https://github.com/fastify/fastify/pull/6731
* ci: add node 26 to test matrices by @Fdawgs in https://github.com/fastify/fastify/pull/6728
* docs(Warnings): remove retired FSTWRN002 warning code by @leestana01 in https://github.com/fastify/fastify/pull/6754
* fix

_[Truncated at 4000 characters — full notes: https://github.com/fastify/fastify/releases/tag/v5.9.0]_

### v5.8.5

- Date: 2026-04-14
- Version: v5.8.5
- Original notes: https://github.com/fastify/fastify/releases/tag/v5.8.5
- Permalink: https://whatsnew.fyi/product/fastify/releases/v5.8.5

- **security** — Fix CVE-2026-33806
- **fixed** — Restore trustProxy function for number and string types and add null check for socketAddr
- **fixed** — Fix port parsing

##### ⚠️ Security Release

This fixes CVE CVE-2026-33806 https://github.com/fastify/fastify/security/advisories/GHSA-247c-9743-5963.

##### What's Changed
* chore: Fix port parsing by @jsumners in https://github.com/fastify/fastify/pull/6603
* chore: upgrade to typescript v6.0.2 by @Tony133 in https://github.com/fastify/fastify/pull/6605
* fix: restore trustProxy function for number and string types, add null check for socketAddr by @mcollina in https://github.com/fastify/fastify/pull/6613
* ci: reduce cron scheduled workflows from daily/weekly to monthly by @Fdawgs in https://github.com/fastify/fastify/pull/6623
* chore: Bump pnpm/action-setup from 4.2.0 to 5.0.0 by @dependabot[bot] in https://github.com/fastify/fastify/pull/6629
* chore: Bump markdownlint-cli2 from 0.21.0 to 0.22.0 by @dependabot[bot] in https://github.com/fastify/fastify/pull/6632
* chore: Bump borp from 0.21.0 to 1.0.0 by @dependabot[bot] in https://github.com/fastify/fastify/pull/6633
* chore: Bump actions/dependency-review-action from 4.8.3 to 4.9.0 by @dependabot[bot] in https://github.com/fastify/fastify/pull/6630
* docs(ecosystem): add @pompelmi/fastify-plugin by @SonoTommy in https://github.com/fastify/fastify/pull/6610

##### New Contributors
* @SonoTommy made their first contribution in https://github.com/fastify/fastify/pull/6610

**Full Changelog**: https://github.com/fastify/fastify/compare/v5.8.4...v5.8.5

### v5.8.4

- Date: 2026-03-23
- Version: v5.8.4
- Original notes: https://github.com/fastify/fastify/releases/tag/v5.8.4
- Permalink: https://whatsnew.fyi/product/fastify/releases/v5.8.4

**Full Changelog**: https://github.com/fastify/fastify/compare/v5.8.3...v5.8.4

### v5.8.3

- Date: 2026-03-23
- Version: v5.8.3
- Original notes: https://github.com/fastify/fastify/releases/tag/v5.8.3
- Permalink: https://whatsnew.fyi/product/fastify/releases/v5.8.3

- **security** — Fix CVE-2026-3635
- **changed** — Allow port to be null in request type definition

##### ⚠️ Security Release

This fixes CVE CVE-2026-3635 https://github.com/fastify/fastify/security/advisories/GHSA-444r-cwp2-x5xf.

##### What's Changed
* docs(readme): add @Tony133 to plugin team by @Tony133 in https://github.com/fastify/fastify/pull/6565
* Updated Plugins-Guide.md; Changed "fastify" to "instance" during plugin registration to showcase that it's added as a child by @kyrylchenko in https://github.com/fastify/fastify/pull/6566
* test: use fastify.test in test case by @climba03003 in https://github.com/fastify/fastify/pull/6568
* docs: use fastify.example in documentation by @climba03003 in https://github.com/fastify/fastify/pull/6567
* docs: add common performance degradation guidance by @maxpetrusenko in https://github.com/fastify/fastify/pull/6520
* docs(server): fix camelCase anchor links in TOC by @Deepvamja in https://github.com/fastify/fastify/pull/6530
* ci(link-checker): fix root-relative links resolution by @barba-rossa in https://github.com/fastify/fastify/pull/6535
* docs: update syntax markdown, absolute paths and links by @Tony133 in https://github.com/fastify/fastify/pull/6569
* docs: clarify content-type parser/schema mismatch is outside threat model by @mcollina in https://github.com/fastify/fastify/pull/6537
* docs: fix incorrect code examples in Reply and Request reference by @mahmoodhamdi in https://github.com/fastify/fastify/pull/6582
* docs: replace redirected npm.im http-errors link by @mcollina in https://github.com/fastify/fastify/pull/6588
* types: Allow port to be null in request type definition by @TristanBarlow in https://github.com/fastify/fastify/pull/6589
* docs: update links by @Tony133 in https://github.com/fastify/fastify/pull/6593
* ci(lock-threads): use shared lock-threads workflow by @Fdawgs in https://github.com/fastify/fastify/pull/6592

##### New Contributors
* @kyrylchenko made their first contribution in https://github.com/fastify/fastify/pull/6566
* @maxpetrusenko made their first contribution in https://github.com/fastify/fastify/pull/6520
* @Deepvamja made their first contribution in https://github.com/fastify/fastify/pull/6530
* @barba-rossa made their first contribution in https://github.com/fastify/fastify/pull/6535
* @mahmoodhamdi made their first contribution in https://github.com/fastify/fastify/pull/6582
* @TristanBarlow made their first contribution in https://github.com/fastify/fastify/pull/6589

**Full Changelog**: https://github.com/fastify/fastify/compare/v5.8.2...v5.8.3

### v5.8.2

- Date: 2026-03-07
- Version: v5.8.2
- Original notes: https://github.com/fastify/fastify/releases/tag/v5.8.2
- Permalink: https://whatsnew.fyi/product/fastify/releases/v5.8.2

- **fixed** — Anchor keyValuePairsReg to prevent quadratic backtracking

##### What's Changed
* docs(ecosystem): add @yeliex/fastify-problem-details by @yeliex in https://github.com/fastify/fastify/pull/6546
* Revert "chore: upgrade borp to v1.0.0" by @climba03003 in https://github.com/fastify/fastify/pull/6564
* docs: document body validation with custom content type parsers by @mcollina in https://github.com/fastify/fastify/pull/6556
* docs(ecosystem): add fastify-file-router by @bhouston in https://github.com/fastify/fastify/pull/6441
* docs: add fastify-svelte-view to Ecosystem list by @matths in https://github.com/fastify/fastify/pull/6453
* fix: anchor keyValuePairsReg to prevent quadratic backtracking by @mcollina in https://github.com/fastify/fastify/pull/6558
* docs: added note on handling of invalid URLs in setNotFoundHandler by @leftieFriele in https://github.com/fastify/fastify/pull/5661
* docs(guides): update codemod links by @OluchiEzeifedikwa in https://github.com/fastify/fastify/pull/6479
* docs: add @glidemq/fastify to community plugins by @avifenesh in https://github.com/fastify/fastify/pull/6560

##### New Contributors
* @yeliex made their first contribution in https://github.com/fastify/fastify/pull/6546
* @matths made their first contribution in https://github.com/fastify/fastify/pull/6453
* @leftieFriele made their first contribution in https://github.com/fastify/fastify/pull/5661
* @OluchiEzeifedikwa made their first contribution in https://github.com/fastify/fastify/pull/6479
* @avifenesh made their first contribution in https://github.com/fastify/fastify/pull/6560

**Full Changelog**: https://github.com/fastify/fastify/compare/v5.8.1...v5.8.2