Deno v1.33.0 — Release Notes & Engineering Impact

Source available — automated, not human-reviewed

Component: deno · Channel: stable. Automated analysis, not a compatibility certification. How this works.

Analysis updated: 2026-11-01.

Breaking-change evidence from the source

- BREAKING(unstable): remove "Deno.serve(handler, options)" overload (#18759)

Read the original context ↗

Source flags breaking changes — review applicability

📄 .MD

✨ Features 6 ⚡ Improvements 5 🔧 Bug Fixes 6 ⚠️ Breaking & Deprecations 1

⚡ Executive Summary (TL;DR)

Deno v1.33.0. Source highlight: BREAKING(unstable): remove "Deno.serve(handler, options)" overload (#18759)

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Who Does This Impact? (Role-Based Analysis)

💻 Software Engineers & Devs

Check the source notes against the package and APIs you use before upgrading.

📊 Product & Engineering Leads

Use the documented changes to assess relevance to your product; release frequency alone is not a quality measure.

⚙️ DevOps & Security

Verify the target version, runtime requirements and rollback procedure in the official documentation.

⚠️ Breaking Changes & Deprecations (1)

- BREAKING(unstable): remove "Deno.serve(handler, options)" overload (#18759)

✨ New Features & Capabilities (6)

Revert "chore(ext/websocket): Add autobahn|testsuite fuzzingclient (#…
feat(bench): add `--no-run` flag (#18433)
feat(cli): don't check permissions for statically analyzable dynamic imports
feat(cli): flatten deno.json configuaration (#17799)
feat(ext/ffi): support marking symbols as optional (#18529)
feat(ext/http): Rework Deno.serve using hyper 1.0-rc3 (#18619)

⚡ Performance & Enhancements (5)

perf(ext/http): avoid spread arg deopt in op_http_wait (#18850)
perf(ext/http): optimize away code based on callback length (#18849)
perf(ext/http): optimize for zero or one-packet response streams (#18834)
perf(ext/http): use smi for slab IDs (#18848)
perf(ext/websocket): various performance improvements (#18862)

🔧 Bug Fixes & Patches (6)

fix(compile): write bytes directly to output file (#18777)
fix(core): Wrap safe collections' argument of primordials (#18750)
fix(coverage): exclude test files (#18748)
fix(dts): `URLPatternComponentResult` groups should have possibly undefined
fix(ext/node): add crypto.sign|verify methods (#18765)
fix(ext/node): fix hash.flush (#18818)

📄 View Raw Release Notes (Original Developer Log)

### 1.33.0 / 2023.04.27 - BREAKING(unstable): remove "Deno.serve(handler, options)" overload (#18759) - Revert "chore(ext/websocket): Add autobahn|testsuite fuzzingclient (#… (#18856) - feat(bench): add `--no-run` flag (#18433) - feat(cli): don't check permissions for statically analyzable dynamic imports (#18713) - feat(cli): flatten deno.json configuaration (#17799) - feat(ext/ffi): support marking symbols as optional (#18529) - feat(ext/http): Rework Deno.serve using hyper 1.0-rc3 (#18619) - feat(ext/kv): add more atomic operation helpers (#18854) - feat(ext/kv): return ok bool from atomic commit (#18873) - feat(ext/url): `URL.canParse` (#18286) - feat(lint): add `Deno.run` to `no-deprecated-deno-api` (#18869) - feat(node/crypto): Elliptic Curve Diffie-Hellman (ECDH) support (#18832) - feat(node/http): implement ClientRequest.setTimeout() (#18783) - feat(task): introduce built-in `unset` command to `deno task` (#18606) - feat: Deprecate Deno.run API in favor of Deno.Command (#17630) (#18866) - fix(compile): write bytes directly to output file (#18777) - fix(core): Wrap safe collections' argument of primordials (#18750) - fix(coverage): exclude test files (#18748) - fix(dts): `URLPatternComponentResult` groups should have possibly undefined key values (#18643) - fix(ext/node): add crypto.sign|verify methods (#18765) - fix(ext/node): fix hash.flush (#18818) - fix(ext/node): implement asymmetric keygen (#18651) - fix(ext/node): improve vm.runInThisContext (#18767) - fix(ext/node): prime generation (#18861) - fix(lsp): show dependency errors for repeated imports (#18807) - fix(npm): only include top level packages in top level node_modules directory (#18824) - fix(test): allow explicit undefined for boolean test options (#18786) - fix(test): handle dispatched exceptions from test functions (#18853) - perf(ext/http): avoid spread arg deopt in op_http_wait (#18850) - perf(ext/http): optimize away code based on callback length (#18849) - perf(ext/http): optimize for zero or one-packet response streams (#18834) - perf(ext/http): use smi for slab IDs (#18848) - perf(ext/websocket): various performance improvements (#18862)

← Older Version Deno v1.32.5 Newer Version → Deno v1.33.1