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typelevel

51 indexed repositories · View on GitHub

cats
Lightweight, modular, and extensible library for functional programming.

Scala · 5465 stars
fs2
Compositional, streaming I/O library for Scala

Scala · 2453 stars
cats-effect
The pure asynchronous runtime for Scala

Scala · 2236 stars
doobie
Functional JDBC layer for Scala.

Scala · 2225 stars
scalacheck
Property-based testing for Scala

Scala · 1964 stars
skunk
A data access library for Scala + Postgres.

Scala · 1667 stars
kind-projector
Compiler plugin for making type lambdas (type projections) easier to write

Scala · 923 stars
frameless
Expressive types for Spark.

Scala · 895 stars
cats-collections
Data structures for pure functional programming in Scala

Scala · 563 stars
kittens
Automatic type class derivation for Cats

Scala · 545 stars
jawn
Jawn is for parsing jay-sawn (JSON)

Scala · 436 stars
log4cats
Logging Tools For Interaction with cats-effect

Scala · 416 stars
sbt-tpolecat
scalac options for the enlightened

Scala · 410 stars
mouse
A small companion to cats

Scala · 376 stars
natchez
functional tracing for cats

Scala · 340 stars
cats-tagless
Library of utilities for tagless final encoded algebras

Scala · 320 stars
fs2-kafka
Functional Kafka Streams for Scala

Scala · 314 stars
cats-mtl
cats transformer type classes.

Scala · 307 stars
fs2-grpc
gRPC implementation for FS2/cats-effect

Scala · 284 stars
cats-parse
A parsing library for the cats ecosystem

Scala · 245 stars
31 more repositories live on View on GitHub

Beginner friendly Everything

Open All

Define deprecation process Open

typelevel/tsc#211 · 1 assignee · Opened Sep 18, 2026
Self-attested maintenance status via MAINTAINERS.md + annual ping (organizational projects) Open

typelevel/tsc#210 · 1 assignee · Opened Sep 18, 2026
`IO#syncStep` drops `uncancelable` and `onCancel` from the returned `IO`, so `Resource` release is skipped Open

Difficulty 4/5 3-5 days Newbie friendliness 68/100

typelevel/cats-effect#4687 · 2 comments · Opened Sep 18, 2026
Seed.apply has different result on Scala 2 and 3 Open

bug

Difficulty 3/5 1-2 days Newbie friendliness 58/100

typelevel/scalacheck#1209 · Opened Sep 16, 2026
take can silently drop a pooled resource when cancelled Open

Difficulty 4/5 3-5 days Newbie friendliness 45/100

typelevel/keypool#708 · 4 comments · Opened Sep 15, 2026
Add http(4s) module Open

Difficulty 5/5 Over a week Newbie friendliness 28/100

typelevel/grackle#946 · 1 comment · Opened Sep 10, 2026
fs2-io is not closing ports when a DatagramChannel is used Open

bug

Difficulty 3/5 1-2 days Newbie friendliness 58/100

typelevel/fs2#3762 · 2 comments · Opened Sep 3, 2026
Extract Discord link to global variable for website Open

Difficulty 3/5 Half a day Newbie friendliness 68/100

typelevel/typelevel.github.com#688 · Opened Sep 1, 2026
`LocalQueue.enqueueBatch` spins forever on a dangling steal tag, and the queue becomes permanently unstealable Open

:beetle: bug

Difficulty 5/5 Over a week Newbie friendliness 35/100

typelevel/cats-effect#4674 · 1 comment · Opened Aug 27, 2026
Come up with a process to champion a PR on a Typelevel project Open

Difficulty 5/5 Over a week Newbie friendliness 35/100

typelevel/tsc#207 · 1 comment · Opened Aug 24, 2026
Forked-run detection fails on sbt 2, reinstating #185: property failures reported as passed, exit 0 Open

Difficulty 4/5 3-5 days Newbie friendliness 48/100

typelevel/scalacheck#1195 · 1 reaction · Opened Aug 20, 2026
Extending `Query` can result in an invalid schema that still parses Open

conformance

Difficulty 3/5 1-2 days Newbie friendliness 48/100

typelevel/grackle#903 · Opened Aug 19, 2026
On MSSQL a DISTINCT subquery can order by a CASE expression that is not in its select list Open

Difficulty 4/5 3-5 days Newbie friendliness 65/100

typelevel/grackle#898 · Opened Aug 18, 2026
Create global Issue config Open

typelevel/tsc#204 · 1 assignee · Opened Aug 10, 2026
Support "bound" instruments Open

Difficulty 4/5 3-5 days Newbie friendliness 35/100

typelevel/otel4s#1322 · Opened Aug 8, 2026
Factory methods for `KafkaProducer` can derive `Parallel` instead of requiring the caller to supply it Open

Difficulty 4/5 3-5 days Newbie friendliness 48/100

typelevel/fs2-kafka#1511 · Opened Aug 6, 2026
Why does Vulcan require exact schema equality in schema lookup Open

Difficulty 4/5 3-5 days Newbie friendliness 35/100

typelevel/vulcan#776 · Opened Jul 31, 2026
TracingPlatform performs undefined behavior in JS that makes it unusable in Wasm Open

:beetle: bug

Difficulty 3/5 1-2 days Newbie friendliness 55/100

typelevel/cats-effect#4644 · 8 comments · Opened Jul 26, 2026
Link affiliate projects that relate to an organization project in its documentation Open

affiliation

typelevel/tsc#203 · 4 comments · 1 assignee · Opened Jul 24, 2026
Rework derivation to use macros Open

Difficulty 5/5 Over a week Newbie friendliness 35/100

typelevel/doobie#2482 · 2 comments · Opened Jul 24, 2026
Address new Sonatype publishing limits Open

typelevel/tsc#202 · 1 reaction · 1 assignee · Opened Jul 23, 2026
Discuss ways to facilitate knowledge transfer to tomorrow's maintainers Open

Difficulty 5/5 Over a week Newbie friendliness 20/100

typelevel/tsc#199 · Opened Jul 21, 2026
Merging Davenverse Projects into maintained libraries and frameworks Open

Difficulty 5/5 Over a week Newbie friendliness 25/100

typelevel/tsc#197 · 3 comments · Opened Jul 21, 2026
Update run returns Int instead of Long Open

Difficulty 2/5 1-3 hours Newbie friendliness 74/100

typelevel/doobie#2479 · Opened Jul 19, 2026
Specify the support policy for organization projects Open

Difficulty 5/5 Over a week Newbie friendliness 25/100

typelevel/tsc#196 · 3 comments · Opened Jul 18, 2026
SQL injection in Channel.fromNameAndProtocol Open

Difficulty 3/5 1-2 days Newbie friendliness 68/100

typelevel/skunk#1339 · 1 reaction · Opened Jul 16, 2026
MapAtomicCell Open

Difficulty 4/5 3-5 days Newbie friendliness 52/100

typelevel/cats-effect#4635 · 1 comment · Opened Jul 12, 2026
Audit of TL Projects both organizational and affliates ensure adherance Open

typelevel/tsc#191 · 4 comments · 1 assignee · Opened Jun 29, 2026
Create a beginner and FP foundation documentation for Typelevel Open

typelevel/tsc#190 · 3 comments · 1 assignee · Opened Jun 29, 2026
"Typelevel Affiliate Project Application" process is defined Open

typelevel/tsc#189 · 3 comments · 1 assignee · Opened Jun 29, 2026
Integrated `Selector`: a ready I/O event can go undelivered for seconds while worker threads sit idle Open

:beetle: bug

Difficulty 4/5 3-5 days Newbie friendliness 35/100

typelevel/cats-effect#4628 · 19 comments · Opened Jun 29, 2026
`Resource.eval` extra cancellation point Open

:beetle: bug

Difficulty 4/5 3-5 days Newbie friendliness 52/100

typelevel/cats-effect#4627 · Opened Jun 28, 2026
Reappropriation of Davenverse projects Open

Difficulty 5/5 Over a week Newbie friendliness 25/100

typelevel/tsc#186 · 2 comments · Opened Jun 27, 2026
Deprecation on projects, and determining inactive projects. Open

typelevel/tsc#185 · 12 comments · 1 assignee · Opened Jun 24, 2026
Replace `peaceiris/actions-gh-pages` with `upload-pages-artifact` Open

Difficulty 3/5 1-2 days Newbie friendliness 48/100

typelevel/sbt-typelevel#900 · Opened Jun 24, 2026
Crossbuild to sbt 2.x Open

Difficulty 4/5 3-5 days Newbie friendliness 38/100

typelevel/sbt-typelevel#899 · 8 comments · 6 reactions · Opened Jun 22, 2026
Add `Fiber#joinOrCancel` Open

:mushroom: enhancement

Difficulty 5/5 Over a week Newbie friendliness 42/100

typelevel/cats-effect#4620 · 36 comments · 1 reaction · Opened Jun 21, 2026
Semantic conventions: generate semantic events Open

enhancement good first issue help wanted module:semconv

Difficulty 3/5 1-2 days Newbie friendliness 48/100

typelevel/otel4s#1285 · Opened Jun 19, 2026
sbt 2 build Open

Difficulty 1/5 Under an hour Newbie friendliness 82/100

typelevel/fs2-grpc#856 · 3 comments · Opened Jun 19, 2026
Overcoming "Error: Experimental Nix Feature 'nix-command' is disabled.. Open

Difficulty 1/5 Under an hour Newbie friendliness 72/100

typelevel/typelevel-nix#271 · 2 comments · Opened Jun 19, 2026
Hikari connection timeouts are delayed when connectEC is exhausted Open

Awaiting Response

Difficulty 4/5 3-5 days Newbie friendliness 45/100

typelevel/doobie#2453 · 3 comments · Opened Jun 16, 2026
Drop JDK 8 and add `-Yfuture-lazy-vals` option for avoid `sun.misc.Unsafe` Open

Difficulty 4/5 3-5 days Newbie friendliness 35/100

typelevel/cats#4871 · 2 comments · 1 reaction · Opened Jun 13, 2026
Scala 3 builds Open

enhancement feature help wanted

Difficulty 4/5 3-5 days Newbie friendliness 35/100

typelevel/frameless#945 · Opened May 25, 2026
Codec.map fails for keys of type java.lang.String Open

Difficulty 2/5 1-3 hours Newbie friendliness 70/100

typelevel/vulcan#749 · 1 comment · Opened May 22, 2026
Why is UnorderedTraverseForHashMap requiring a Hash constraint Open

Difficulty 4/5 3-5 days Newbie friendliness 48/100

typelevel/cats-collections#821 · Opened May 15, 2026
Public hook for appending commands to the "Check headers and formatting" lint step Open

Difficulty 3/5 1-2 days Newbie friendliness 68/100

typelevel/sbt-typelevel#888 · Opened May 7, 2026
Allow raw GHA expressions in matrix axes (and outputs) Open

Difficulty 4/5 3-5 days Newbie friendliness 55/100

typelevel/sbt-typelevel#887 · 1 comment · Opened May 7, 2026
Converge on a single nomenclature for fiber blocking in docs Open

:books: docs good first issue

Difficulty 2/5 1-3 hours Newbie friendliness 74/100

typelevel/cats-effect#4597 · 3 reactions · Opened May 5, 2026
TCP connection pool design advice Open

Difficulty 5/5 Over a week Newbie friendliness 25/100

typelevel/fs2#3719 · 2 comments · Opened May 1, 2026
Add derived for Get, Put, Meta (single-field Products) and document Scala 3 recursion pitfalls Open

Difficulty 4/5 3-5 days Newbie friendliness 55/100

typelevel/doobie#2421 · 3 comments · 1 reaction · Opened Apr 24, 2026

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