--- title: Open Source url: "https://www.iteratorshq.com/open-source/" type: page description: "Iterators builds and maintains open source Scala libraries — kebs, sealed-monad, http4s-stir and baklava — and runs ScalaWAW, Warsaw's Scala community." published: 2026-06-16 updated: 2026-10-15 author: ajaguscik site: Iterators --- # Open Source Open Source & Community # Code we write.\ Community we build We build tools we wished existed. Our open source libraries are used by Scala teams worldwide to eliminate boilerplate, simplify error handling, and ship faster. Most live under [github.com/theiterators](https://github.com/theiterators), and madrileño has its own home at [github.com/madrileno-dev](https://github.com/madrileno-dev). **Scala Ambassador** Łukasz Sowa, Scala Center **40 public repositories** [github.com/theiterators](https://github.com/theiterators) **Talks & conferences** ScalaWAW, Lambda Days, Scalar Scala AI-first ## [madrileño](https://github.com/madrileno-dev/madrileno) An AI-first Scala 3 backend template built on http4s, Skunk and cats-effect. MCP servers give your coding assistant a live compile-and-test loop, and the docs double as its knowledge base. Auth, scheduled jobs, an outbox and feature flags are already in place — one script turns it into your project. 1 fork 4 stars Contributors: [![luksow](https://avatars.githubusercontent.com/u/149984?s=56&v=4)](https://github.com/luksow) [![jglodek](https://avatars.githubusercontent.com/u/879088?s=56&v=4)](https://github.com/jglodek) Scala ## [kebs](https://github.com/theiterators/kebs) A Scala library to eliminate boilerplate. Automatically derives typeclass instances for JSON codecs, DB column mappings, and HTTP unmarshallers across 17+ modules — Slick, Circe, Doobie, http4s, Play JSON and more. Works with Scala 2.13 and Scala 3. 16 forks 159 stars Contributors: [![pk044](https://avatars.githubusercontent.com/u/27566245?s=56&v=4)](https://github.com/pk044) [![luksow](https://avatars.githubusercontent.com/u/149984?s=56&v=4)](https://github.com/luksow) [![marcin-rzeznicki](https://avatars.githubusercontent.com/u/3391348?s=56&v=4)](https://github.com/marcin-rzeznicki) [![zofja](https://avatars.githubusercontent.com/u/44227379?s=56&v=4)](https://github.com/zofja) Scala ## [sealed-monad](https://github.com/theiterators/sealed-monad) A Scala library for business logic-oriented error handling with for-comprehension support. EitherT on steroids — type-safe, readable, and perfect for taming complex error paths without nested pattern matching. 7 forks 23 stars Contributors: [![luksow](https://avatars.githubusercontent.com/u/149984?s=56&v=4)](https://github.com/luksow) [![pk044](https://avatars.githubusercontent.com/u/27566245?s=56&v=4)](https://github.com/pk044) [![jglodek](https://avatars.githubusercontent.com/u/879088?s=56&v=4)](https://github.com/jglodek) [![marcin-rzeznicki](https://avatars.githubusercontent.com/u/3391348?s=56&v=4)](https://github.com/marcin-rzeznicki) Scala ## [http4s-stir](https://github.com/theiterators/http4s-stir) Pekko HTTP-style DSL directives for http4s, powered by cats-effect’s IO. Supports ~85% of Pekko HTTP directives and runs on JVM, Scala.js, and Scala Native — compatible with Scala 2.13 and Scala 3. 0 forks 34 stars Contributors: [![luksow](https://avatars.githubusercontent.com/u/149984?s=56&v=4)](https://github.com/luksow) [![pk044](https://avatars.githubusercontent.com/u/27566245?s=56&v=4)](https://github.com/pk044) Scala ## [baklava](https://github.com/theiterators/baklava) Generate OpenAPI specs, HTML docs, or TypeScript client interfaces directly from routing tests. Supports Pekko HTTP, http4s, ScalaTest, Specs2, and MUnit — API documentation as a natural byproduct of testing. 0 forks 8 stars Contributors: [![luksow](https://avatars.githubusercontent.com/u/149984?s=56&v=4)](https://github.com/luksow) [![pk044](https://avatars.githubusercontent.com/u/27566245?s=56&v=4)](https://github.com/pk044) [![kristerr](https://avatars.githubusercontent.com/u/9675500?s=56&v=4)](https://github.com/kristerr) [![rpiotrow](https://avatars.githubusercontent.com/u/355631?s=56&v=4)](https://github.com/rpiotrow) [![jkozlovvski](https://avatars.githubusercontent.com/u/44581245?s=56&v=4)](https://github.com/jkozlovvski) Community ## ScalaWAW —\ Warsaw’s Scala Community Since 2015, we’ve been building the Scala community in Warsaw. ScalaWAW is the largest informal gathering of Scala developers in Poland — meetups, talks, hackathons and beer sessions for everyone from beginners to language contributors. **905** members on Meetup.com **4.9 / 5 ★** average rating **61** events since 2015 We organize and sponsor ScalaWAW. Our managing partner Łukasz Sowa has led the group since day one and serves as an official Scala Ambassador appointed by the Scala Center. Topics range from functional programming patterns and type-level Scala, to build tooling, Akka, and Apache Spark. Guests have included international speakers like Li Haoyi and Bartosz Milewski. [Join us on Meetup](https://www.meetup.com/ScalaWAW/) ![ScalaWAW meetup — Warsaw's Scala Community](https://www.iteratorshq.com/wp-content/uploads/2026/06/scalawaw-photo.webp)