# Crystal changelog

> A programming language with Ruby-like syntax and compile-time type checking.

- Vendor: Crystal Language
- Category: Languages & Runtimes
- Official site: https://crystal-lang.org
- Tracked by: What's New (https://whatsnew.fyi/product/crystal)
- Harvested from: GitHub (crystal-lang/crystal)
- 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

### 1.21.0

- Date: 2026-07-16
- Version: 1.21.0
- Original notes: https://github.com/crystal-lang/crystal/releases/tag/1.21.0
- Permalink: https://whatsnew.fyi/product/crystal/releases/1.21.0

- **removed** — Disable automatic fallback to legacy PCRE
- **changed** — Release Execution Contexts
- **added** — Add %W percent string array literals with interpolation
- **added** — Add TypeNode#all_methods that includes the type's ancestor's methods
- **added** — Align long-only options in OptionParser help
- **added** — Make Channel(T) an Iterator(T)
- **added** — Add support for OpenSSL 4.0
- **added** — Support OpenSSL 4.x DLLs on Windows MSVC
- **added** — Add Socket#sendfile (and Crystal::EventLoop::Socket#sendfile)
- **added** — Add HTTP::WebSocket#receive as a synchronous call
- **added** — Add Crystal::EventLoop::FileDescriptor#pread
- **added** — Add without_main flag
- **changed** — OpenBSD: use kqueue event loop by default
- **added** — Support nested root properties in JSON::Field
- **added** — Add URI::Params::Field(ignore:), ignore_serialize, ignore_deserialize
- **added** — Allow chaining #should, #should_not expectations
- **added** — Expose Path#kind
- **added** — Add splat overloads for Process.capture, .run and .new
- **added** — Add Process::Status.[] constructor
- **added** — Add String#present?
- **added** — Add UUID.v6 and .v8 generators

###### Breaking changes

###### stdlib

- _(runtime)_ Release: Execution Contexts ([#17100], [#17104], thanks @ysbaddaden)
- _(text)_ Disable automatic fallback to legacy `PCRE` ([#16924], thanks @straight-shoota)

[#16924]: https://github.com/crystal-lang/crystal/pull/16924
[#17100]: https://github.com/crystal-lang/crystal/pull/17100
[#17104]: https://github.com/crystal-lang/crystal/pull/17104

###### Features

###### lang

- Add `%W` percent string array literals with interpolation ([#16919], thanks @straight-shoota)
- _(macros)_ Add `TypeNode#all_methods` that includes the type's ancestor's methods ([#16902], thanks @Blacksmoke16)

[#16902]: https://github.com/crystal-lang/crystal/pull/16902
[#16919]: https://github.com/crystal-lang/crystal/pull/16919

###### stdlib

- _(cli)_ Align long-only options in OptionParser help ([#16914], thanks @kojix2)
- _(collection)_ Make `Channel(T)` an `Iterator(T)` ([#16916], thanks @jgaskins)
- _(crypto)_ Add support for OpenSSL 4.0 ([#16839], thanks @straight-shoota)
- _(crypto)_ Support OpenSSL 4.x DLLs on Windows MSVC ([#17116], thanks @HertzDevil)
- _(networking)_ **[experimental]** Add `Socket#sendfile` (and `Crystal::EventLoop::Socket#sendfile`) ([#16665], [#17133], thanks @ysbaddaden, @straight-shoota)
- _(networking)_ Add `HTTP::WebSocket#receive` as a synchronous call ([#16689], thanks @jgaskins)
- _(runtime)_ Add `Crystal::EventLoop::FileDescriptor#pread` ([#17068], thanks @ysbaddaden)
- _(runtime)_ Add `without_main` flag ([#17074], thanks @kojix2)
- _(runtime)_ OpenBSD: use kqueue event loop by default ([#17123], thanks @ysbaddaden)
- _(serialization)_ Support nested `root` properties in `JSON::Field` ([#17016], thanks @tcoatswo)
- _(serialization)_ Add `URI::Params::Field(ignore:)`, `ignore_serialize`, `ignore_deserialize` ([#17029], thanks @trypsynth)
- _(specs)_ Allow chaining `#should`, `#should_not` expectations ([#17020], thanks @straight-shoota)
- _(system)_ Expose `Path#kind` ([#16917], thanks @Sija)
- _(system)_ Add splat overloads for `Process.capture`, `.run` and `.new` ([#16975], thanks @straight-shoota)
- _(system)_ Add `Process::Status.[]` constructor ([#17003], thanks @straight-shoota)
- _(text)_ Add `String#present?` ([#16930], thanks @Sija)
- _(text)_ Add `UUID.v6` and `.v8` generators ([#17010], thanks @trypsynth)

[#16665]: https://github.com/crystal-lang/crystal/pull/16665
[#16689]: https://github.com/crystal-lang/crystal/pull/16689
[#16839]: https://github.com/crystal-lang/crystal/pull/16839
[#16914]: https://github.com/crystal-lang/crystal/pull/16914
[#16916]: https://github.com/crystal-lang/crystal/pull/16916
[#16917]: https://github.com/crystal-lang/crystal/pull/16917
[#16930]: https://github.com/crystal-lang/crystal/pull/16930
[#16975]: https://github.com/crystal-lang/crystal/pull/16975
[#17003]: https://github.com/crystal-lang/crystal/pull/17003
[#17010]: https://github.com/crystal-lang/crystal/pull/17010
[#17016]: https://github.com/crystal-lang/crystal/pull/17016
[#17020]: https://github.com/crystal-lang/crystal/pull/17020
[#17029]: https://github.com/crystal-lang/crystal/pull/17029
[#17068]: https://github.com/crystal-lang/crystal/pull/17068
[#17074]: https://github.com/crystal-lang/crystal/pull/17074
[#17116]: https://github.com/crystal-lang/crystal/pull/17116
[#17123]: https://github.com/crystal-lang/crystal/pull/17123
[#17133]: https://github.com/crystal-lang/crystal/pull/17133

###### compiler

- _(cli)_ Classify compiler exit reasons ([#17028], thanks @straight-shoota)
- _(debugger)_ Improve proc debug metadata ([#16830], thanks @skuznetsov)
- _(debugger)_ Emit debug metadata for constants and class vars ([#16831], thanks @skuznetsov)
- _(debugger)_ Improve LLDB collection formatters ([#16832], thanks @skuznetsov)
- _(parser)_ Add `ASTNode#inspect` ([#16699], thanks @straight-shoota)
- _(parser)_ Parse `MacroVar` with empty expressions: `%var{}` ([#16772], thanks @straight-shoot

_[Truncated at 4000 characters — full notes: https://github.com/crystal-lang/crystal/releases/tag/1.21.0]_

### 1.20.3

- Date: 2026-07-02
- Version: 1.20.3
- Original notes: https://github.com/crystal-lang/crystal/releases/tag/1.20.3
- Permalink: https://whatsnew.fyi/product/crystal/releases/1.20.3

- **security** — add max_nesting to YAML::PullParser
- **security** — add alias vs anchor ratio check to YAML::PullParser
- **changed** — memoize anchor name in YAML::PullParser

###### Bugfixes

###### stdlib

- _(serialization)_ **[security]** add `max_nesting` to `YAML::PullParser` ([#17107], thanks @ysbaddaden)
- _(serialization)_ **[security]** add alias vs anchor ratio check to `YAML::PullParser` ([#17109], thanks @ysbaddaden)

[#17107]: https://github.com/crystal-lang/crystal/pull/17107
[#17109]: https://github.com/crystal-lang/crystal/pull/17109

###### Refactor

###### stdlib

- _(serialization)_ `YAML::PullParser`: memoize anchor name ([#17108], thanks @ysbaddaden)

[#17108]: https://github.com/crystal-lang/crystal/pull/17108

###### Infrastructure

- Add changelog for 1.20.3 ([#17110], thanks @ysbaddaden)

[#17110]: https://github.com/crystal-lang/crystal/pull/17110

### 1.20.2

- Date: 2026-05-15
- Version: 1.20.2
- Original notes: https://github.com/crystal-lang/crystal/releases/tag/1.20.2
- Permalink: https://whatsnew.fyi/product/crystal/releases/1.20.2

- **fixed** — Simplify Sync::Mutex#synchronize proc type constraints
- **fixed** — Range#sample eventually loses randomness

###### Bugfixes

###### stdlib

- _(concurrency)_ **[regression]** Simplify `Sync::Mutex#synchronize` proc type constraints ([#16904], [#16937], thanks @ysbaddaden)
- _(runtime)_ `Range#sample` eventually loses randomness ([#16909], thanks @ysbaddaden)

[#16904]: https://github.com/crystal-lang/crystal/pull/16904
[#16909]: https://github.com/crystal-lang/crystal/pull/16909
[#16937]: https://github.com/crystal-lang/crystal/pull/16937

###### Infrastructure

- Changelog for 1.20.2 ([#16945], thanks @straight-shoota)

[#16945]: https://github.com/crystal-lang/crystal/pull/16945

### 1.20.1

- Date: 2026-04-29
- Version: 1.20.1
- Original notes: https://github.com/crystal-lang/crystal/releases/tag/1.20.1
- Permalink: https://whatsnew.fyi/product/crystal/releases/1.20.1

- **fixed** — Fix issues in OpenSSL Kernel TLS
- **changed** — OpenSSL Kernel TLS support should be opt-in
- **added** — Add HTTP::Headers#to_json and #to_yaml
- **fixed** — Range#sample eventually loses randomness
- **fixed** — Don't parse debug sections from bare threads
- **fixed** — Fix lexing macro delimiter state inside literals
- **fixed** — Revert "Refactor Formatter code for simplification"

###### Bugfixes

###### stdlib

- _(crypto)_ Fix issues in OpenSSL Kernel TLS ([#16888], thanks @ysbaddaden)
- _(crypto)_ OpenSSL Kernel TLS support should be opt-in ([#16897], thanks @ysbaddaden)
- _(networking)_ **[regression]** Add `HTTP::Headers#to_json` and `#to_yaml` ([#16890], thanks @straight-shoota)
- _(runtime)_ **[regression]** `Range#sample` eventually loses randomness ([#16853], thanks @ysbaddaden)
- _(runtime)_ don't parse debug sections from bare threads ([#16877], thanks @ysbaddaden)

[#16853]: https://github.com/crystal-lang/crystal/pull/16853
[#16877]: https://github.com/crystal-lang/crystal/pull/16877
[#16888]: https://github.com/crystal-lang/crystal/pull/16888
[#16890]: https://github.com/crystal-lang/crystal/pull/16890
[#16897]: https://github.com/crystal-lang/crystal/pull/16897

###### compiler

- _(parser)_ **[regression]** Fix lexing macro delimiter state inside literals ([#16892], thanks @straight-shoota)

[#16892]: https://github.com/crystal-lang/crystal/pull/16892

###### tools

- _(formatter)_ **[regression]** Revert "Refactor `Formatter` code for simplification" ([#16885], thanks @straight-shoota)

[#16885]: https://github.com/crystal-lang/crystal/pull/16885

###### Refactor

###### stdlib

- _(runtime)_ Refactor `Exception::CallStack` for better boundaries ([#16896], thanks @straight-shoota)

[#16896]: https://github.com/crystal-lang/crystal/pull/16896

###### Infrastructure

- Changelog for 1.20.1 ([#16898], thanks @straight-shoota)

[#16898]: https://github.com/crystal-lang/crystal/pull/16898

### 1.19.2

- Date: 2026-04-27
- Version: 1.19.2
- Original notes: https://github.com/crystal-lang/crystal/releases/tag/1.19.2
- Permalink: https://whatsnew.fyi/product/crystal/releases/1.19.2

- **security** — HTTP::Server is no longer vulnerable to request smuggling
- **fixed** — Range#sample eventually loses randomness

###### Security

###### stdlib

- _(networking)_ `HTTP::Server` is no longer vulnerable to request smuggling ([#16862], thanks @ysbaddaden)

[#16862]: https://github.com/crystal-lang/crystal/pull/16862

###### Bugfixes

###### stdlib

- **[regression]** `Range#sample` eventually loses randomness ([#16866], thanks @straight-shoota, @ysbaddaden)

[#16866]: https://github.com/crystal-lang/crystal/pull/16866

###### Infrastructure

- Changelog for 1.19.2 ([#16893], thanks @ysbaddaden)
- _(ci)_ Drop `update: true` from `msys2/setup-msys` ([#16868], thanks @straight-shoota)

[#16893]: https://github.com/crystal-lang/crystal/pull/16893
[#16868]: https://github.com/crystal-lang/crystal/pull/16868

### 1.20.0

- Date: 2026-04-17
- Version: 1.20.0
- Original notes: https://github.com/crystal-lang/crystal/releases/tag/1.20.0
- Permalink: https://whatsnew.fyi/product/crystal/releases/1.20.0

- **security** — Fix HTTP::Server is no longer vulnerable to request smuggling
- **added** — Add #select and #reject to HashLiteral and NamedTupleLiteral in macros
- **changed** — Refine error message for unsupported named arguments in macros
- **added** — Add short option bundling for OptionParser
- **added** — Add Kernel TLS support to custom OpenSSL::BIO
- **added** — Add IO#read_greedy
- **added** — Add FileUtils#rm_f
- **added** — Add IO::PrefixSuffixBuffer for capturing truncated streams
- **changed** — Support LLVM 22.1 and 23.0
- **added** — Add Sec-WebSocket-Protocol checks to HTTP::WebSocket::Protocol
- **added** — Add support for Sec-WebSocket-Protocol to HTTP::WebSocketHandler
- **added** — Add HTTP::Response#content_type and #content_length as convenient accessors
- **added** — Detect OAuth error in payload
- **added** — Add Fiber::ExecutionContext::ThreadPool
- **added** — Add Pointer#align_up and #align_down
- **changed** — Detach execution context scheduler from running thread during blocking syscall
- **added** — Forward API docs for properties in record macro
- **added** — Add Crystal::Lock
- **added** — Add io_uring event loop for Linux
- **changed** — Use FdLock on all targets
- **added** — Add Process.new with args instead of command, args
- **added** — Add Process.run(args) without command
- **added** — Add Process.run?
- **added** — Add Process.capture
- **added** — Add StringScanner#scan, #check, and #skip overloads for Int
- **added** — Add StringScanner#peek_behind
- **added** — Add convenience methods to StringScanner
- **changed** — Improve cursor window format in StringScanner#inspect
- **changed** — Prefer modern linker (mold or lld)
- **added** — Add @[TargetFeature] annotation
- **added** — Parse ProcNotation with empty arg parenthesis: () ->
- **added** — Add --base-path for crystal docs
- **fixed** — Fix decode gzip MTIME as UInt32
- **changed** — OpenSSL sockets shouldn't flush on read
- **fixed** — Fix typo in digest.cr
- **fixed** — Fix MIME.parse_media_type invalid character check

###### Security

###### stdlib

- _(networking)_ Fix `HTTP::Server` is no longer vulnerable to request smuggling ([GHSA-wqh5-7w63-pm68])

[GHSA-wqh5-7w63-pm68]: https://github.com/crystal-lang/crystal/security/advisories/GHSA-wqh5-7w63-pm68

###### Features

###### lang

- _(macros)_ Add `#select` and `#reject` to `HashLiteral` and `NamedTupleLiteral` ([#16558], thanks @Blacksmoke16)
- _(macros)_ Refine error message for unsupported named arguments in macros ([#16576], thanks @hahwul)

[#16558]: https://github.com/crystal-lang/crystal/pull/16558
[#16576]: https://github.com/crystal-lang/crystal/pull/16576

###### stdlib

- _(cli)_ Add short option bundling for `OptionParser` ([#16770], thanks @Qard)
- _(crypto)_ Add Kernel TLS support to custom `OpenSSL::BIO` ([#16646], thanks @ysbaddaden)
- _(files)_ Add `IO#read_greedy` ([#16535], thanks @BlobCodes)
- _(files)_ Add `FileUtils#rm_f` ([#12832], thanks @zw963)
- _(files)_ Add `IO::PrefixSuffixBuffer` for capturing truncated streams ([#16774], thanks @straight-shoota)
- _(llvm)_ Support LLVM 22.1 and 23.0 ([#16631], thanks @HertzDevil)
- _(networking)_ Add `Sec-WebSocket-Protocol` checks to `HTTP::WebSocket::Protocol` ([#16600], [#16671], thanks @antondalgren, @straight-shoota)
- _(networking)_ Add support for `Sec-WebSocket-Protocol` to `HTTP::WebSocketHandler` ([#16574], thanks @antondalgren)
- _(networking)_ Add `HTTP::Response#content_type` and `#content_length` as convenient accessors ([#16712], thanks @CTC97)
- _(networking)_ Detect `OAuth` error in payload ([#16634], [#16828], thanks @jgaskins, @Sija)
- _(runtime)_ Add `Fiber::ExecutionContext::ThreadPool` ([#15885], [#16750], thanks @ysbaddaden)
- _(runtime)_ Add `Pointer#align_up` and `#align_down` ([#16585], thanks @BlobCodes)
- _(runtime)_ Detach execution context scheduler from running thread during blocking syscall ([#15871], [#16679], thanks @ysbaddaden)
- _(runtime)_ Forward API docs for properties in `record` macro ([#16172], [#16834], thanks @Vici37, @ysbaddaden)
- _(runtime)_ Add `Crystal::Lock` ([#16768], thanks @ysbaddaden)
- _(runtime)_ Add io_uring event loop (linux) ([#16264], thanks @ysbaddaden)
- _(system)_ Use `FdLock` on all targets ([#16569], thanks @ysbaddaden)
- _(system)_ Add `Process.new` with `args` instead of `command, args` ([#16681], thanks @straight-shoota)
- _(system)_ Add `Process.run(args)` without `command` ([#16739], thanks @straight-shoota)
- _(system)_ Add `Process.run?` ([#16738], thanks @straight-shoota)
- _(system)_ Add `Process.capture` ([#16773], thanks @straight-shoota)
- _(text)_ Add `StringScanner#scan`, `#check`, and `#skip` overloads for `Int` ([#16557], thanks @jneen)
- _(text)_ Add `StringScanner#peek_behind` ([#16593], thanks @jneen)
- _(text)_ Add convenience methods to `StringScanner` ([#16595], thanks @jneen)
- _(text)_ Improve cursor window format in `StringScanner#inspect` ([#16594], thanks @jneen)

[#12832]: https://github.com/crystal-lang/crystal/pull/12832
[#15871]: https://github.com/crystal-lang/crystal/pull/15871
[#15885]: https://github.com/crystal-lang/crystal/pull/15885
[#16172]: https://github.com/crystal-lang/crystal/pull/16172
[#16264]: https://github.com/crystal-lang/crystal/pull/16264
[#16535]: https://github.com/crystal-lang/crystal/pull/16535
[#16557]: https://github.com/crystal-lang/crystal/pull/16557
[#16569]: https://github.com/crystal-lang/crystal/pull/16569
[#16574]: https://github.com/crystal-lang/crystal/pull/16574
[#16585]: https://github.com/crystal-lang/crystal/pull/16585
[#16593]: https://github.com/crystal-lang/crystal/pull/16593
[#16594]: https://github.com/crystal-lang/crystal/pull/16594
[#16595]: https://github.com/crystal-lang/crystal/pull/16595
[#16600]: https://github.com/crystal-lang/crystal/pull/16600
[#16631]: https://github.com/crystal-lang/crystal/pull/16631
[#16634]: https://github.com/crystal-lang/crystal/pull/16634
[#16646]: https://github.com/crystal-lang/crystal/p

_[Truncated at 4000 characters — full notes: https://github.com/crystal-lang/crystal/releases/tag/1.20.0]_

### 1.19.1

- Date: 2026-01-20
- Version: 1.19.1
- Original notes: https://github.com/crystal-lang/crystal/releases/tag/1.19.1
- Permalink: https://whatsnew.fyi/product/crystal/releases/1.19.1

- **fixed** — Fix kqueue timer duration calculation in concurrency
- **fixed** — Fix time calculations in IOCP and Monitor thread in concurrency

###### Bugfixes

###### stdlib

- _(concurrency)_ **[regression]** Fix kqueue timer duration calculation ([#16581], thanks @skuznetsov)
- _(concurrency)_ **[regression]** time calculations in IOCP and Monitor thread ([#16583], thanks @ysbaddaden)

[#16581]: https://github.com/crystal-lang/crystal/pull/16581
[#16583]: https://github.com/crystal-lang/crystal/pull/16583

###### Infrastructure

- Changelog for 1.19.1 ([#16590], thanks @ysbaddaden)

[#16590]: https://github.com/crystal-lang/crystal/pull/16589

### 1.19.0

- Date: 2026-01-15
- Version: 1.19.0
- Original notes: https://github.com/crystal-lang/crystal/releases/tag/1.19.0
- Permalink: https://whatsnew.fyi/product/crystal/releases/1.19.0

- **removed** — Require OpenSSL 1.1.1+ or LibreSSL 3+
- **added** — Add compiler flag values to macros
- **added** — Add yielding variant of StringLiteral#gsub
- **added** — Support StringLiteral#split(RegexLiteral)
- **added** — Add StringLiteral#match
- **changed** — Make all overloads of ArrayLiteral#[] return nil on out of bounds
- **added** — Add NamedTuple#reverse_merge
- **changed** — Pad Hash#inspect, Tuple#inspect before { from first element
- **added** — Add Set#map!
- **added** — Add Hash#transform_keys!
- **changed** — Enhance error message for Hash#[] when key is wrong type for default block
- **added** — Add Sync::Mutex and Sync::RWLock
- **added** — Add Sync::ConditionVariable
- **added** — Import Sync::Exclusive and Sync::Shared
- **added** — Add OpenSSL::SSL::Context::Server#on_server_name for SNI
- **changed** — Loosen type restrictions in StaticFileHandler helper methods from File to IO
- **added** — Add IPSocket#ipv6_only
- **added** — Expose flags hint for getaddrinfo
- **added** — Add Int.from_digits as inverse of Int#digits
- **added** — Add BigInt.from_digits
- **added** — Add Int#tdivmod

###### Breaking changes

###### stdlib

- _(crypto)_ Require OpenSSL 1.1.1+ or LibreSSL 3+ ([#16480], thanks @ysbaddaden)

[#16480]: https://github.com/crystal-lang/crystal/pull/16480

###### Features

###### lang

- _(macros)_ **[breaking]** Add compiler flag values ([#16310], thanks @straight-shoota)
- _(macros)_ Add yielding variant of `StringLiteral#gsub` ([#16378], thanks @Blacksmoke16)
- _(macros)_ Support `StringLiteral#split(RegexLiteral)` ([#16423], thanks @HertzDevil)
- _(macros)_ Add `StringLiteral#match` ([#16464], thanks @HertzDevil)
- _(macros)_ Make all overloads of `ArrayLiteral#[]` return `nil` on out of bounds ([#16453], thanks @HertzDevil)

[#16310]: https://github.com/crystal-lang/crystal/pull/16310
[#16378]: https://github.com/crystal-lang/crystal/pull/16378
[#16423]: https://github.com/crystal-lang/crystal/pull/16423
[#16464]: https://github.com/crystal-lang/crystal/pull/16464
[#16453]: https://github.com/crystal-lang/crystal/pull/16453

###### stdlib

- _(collection)_ Add `NamedTuple#reverse_merge` ([#16229], thanks @andrykonchin)
- _(collection)_ Pad `Hash#inspect`, `Tuple#inspect` before `{` from first element ([#16245], thanks @andrykonchin)
- _(collection)_ Add `Set#map!` ([#16271], thanks @andrykonchin)
- _(collection)_ Add `Hash#transform_keys!` ([#16280], thanks @andrykonchin)
- _(collection)_ Enhance error message for `Hash#[]` when key is wrong type for default block ([#16442], thanks @Blacksmoke16)
- _(concurrency)_ Add `Sync::Mutex` and `Sync::RWLock` ([#16399], thanks @ysbaddaden)
- _(concurrency)_ Add `Sync::ConditionVariable` ([#16440], thanks @ysbaddaden)
- _(concurrency)_ Import `Sync::Exclusive` and `Sync::Shared` ([#16487], thanks @ysbaddaden)
- _(crypto)_ Add `OpenSSL::SSL::Context::Server#on_server_name` for SNI ([#16452], [#16525], thanks @carlhoerberg, @straight-shoota)
- _(networking)_ Loosen type restrictions in `StaticFileHandler` helper methods from `File` to `IO` ([#16238], thanks @andrykonchin)
- _(networking)_ Add `IPSocket#ipv6_only` ([#16347], thanks @stakach)
- _(networking)_ Expose `flags` hint for `getaddrinfo` ([#16528], thanks @stakach)
- _(numeric)_ Add `Int.from_digits` as inverse of `Int#digits` ([#16237], [#16566], thanks @andrykonchin, @ysbaddaden)
- _(numeric)_ Add `BigInt.from_digits` ([#16259], thanks @HertzDevil)
- _(numeric)_ Add `Int#tdivmod` ([#16258], thanks @andrykonchin)
- _(runtime)_ Add `Proc#[]` as alias to `#call` ([#16220], thanks @andrykonchin)
- _(runtime)_ Add `#unshift`, `#pop` and `#pop?` to `Crystal::PointerLinkedList` ([#16287], thanks @ysbaddaden)
- _(runtime)_ Add `Random.next_bool` and `.next_int` ([#16297], thanks @ysbaddaden)
- _(runtime)_ Add `Random#split` and `#split_internal` API for splittable PRNGs ([#16342], [#16495], thanks @ysbaddaden)
- _(runtime)_ Add `Pointer#fill` ([#16338], thanks @straight-shoota)
- _(runtime)_ Add `Crystal::PointerLinkedList#first?` ([#16400], thanks @ysbaddaden)
- _(runtime)_ Ensure single reader and writer to system fd on Unix ([#16209], thanks @ysbaddaden)
- _(runtime)_ Protect `Box.unbox` from dereferencing null pointer ([#16514], thanks @straight-shoota)
- _(runtime)_ Register execution context schedulers with the event loop ([#16519], thanks @ysbaddaden)
- _(runtime)_ Add `Fiber::ExecutionContext::Scheduler.current?` ([#16521], thanks @ysbaddaden)
- _(runtime)_ Move execution context event loop lock to each event loop ([#16520], thanks @ysbaddaden)
- _(serialization)_ Support deserialization of YAML anchors of value types ([#16186], thanks @HertzDevil)
- _(serialization)_ Add end locations to scalars and aliases in `YAML::Nodes.parse` ([#16187], thanks @HertzDevil)
- _(serialization)_ Set `JSON::SerializableError#attribute` when appropriate ([#16158], thanks @spuun)
- _(serialization)_ Support large JSON files ([#16211], thanks @RX14)
- _(serialization)_ Add `YAML::Nodes.parse_all` ([#16247], thanks @HertzDevil)
- _(specs)_ Rescale execution c

_[Truncated at 4000 characters — full notes: https://github.com/crystal-lang/crystal/releases/tag/1.19.0]_

### 1.18.2

- Date: 2025-10-21
- Version: 1.18.2
- Original notes: https://github.com/crystal-lang/crystal/releases/tag/1.18.2
- Permalink: https://whatsnew.fyi/product/crystal/releases/1.18.2

- **fixed** — Revert type restriction for IO#read_bytes
- **fixed** — Fix Fiber::ExecutionContext.default_workers_count to avoid taking into account unsupported values

###### Bugfixes

###### stdlib

- _(files)_ **[regression]** Revert type restriction for `IO#read_bytes` ([#16231], thanks @straight-shoota)
- _(runtime)_ Fix `Fiber::ExecutionContext.default_workers_count` to avoid taking into account unsupported values ([#16227], thanks @Sija)

[#16231]: https://github.com/crystal-lang/crystal/pull/16231
[#16227]: https://github.com/crystal-lang/crystal/pull/16227

###### Infrastructure

- Changelog for 1.18.2 ([#16243], thanks @matiasgarciaisaia)

[#16243]: https://github.com/crystal-lang/crystal/pull/16243

### 1.18.1

- Date: 2025-10-17
- Version: 1.18.1
- Original notes: https://github.com/crystal-lang/crystal/releases/tag/1.18.1
- Permalink: https://whatsnew.fyi/product/crystal/releases/1.18.1

- **fixed** — Revert adding type restrictions on HTTP::WebSocket#send etc.
- **fixed** — Fix allow space after base type in enum def

###### Bugfixes

###### stdlib

- _(networking)_ **[regression]** Revert adding type restrictions on `HTTP::WebSocket#send` etc. ([#16218], thanks @straight-shoota)

[#16218]: https://github.com/crystal-lang/crystal/pull/16218

###### compiler

- _(parser)_ **[regression]** Fix allow space after base type in enum def ([#16217], thanks @straight-shoota)

[#16217]: https://github.com/crystal-lang/crystal/pull/16217

###### Infrastructure

- Changelog for 1.18.1 ([#16224], thanks @matiasgarciaisaia)

[#16224]: https://github.com/crystal-lang/crystal/pull/16224