Open Source Contributions
The world runs on open source software, and its excellence comes from community-driven critique, audits, and contributions. We've been part of that for over a decade — as authors of libraries and tools, and as contributors to projects we depend on.
64
Haskell packages on Hackage
320k+
downloads of those packages
~300
public repositories on GitHub
Featured projects
OpenChronology
A timeline editor built on exact arithmetic
Event times are arbitrary-precision rational numbers, so moments never drift or collide through floating-point rounding — whether they're centuries or microseconds apart. It runs in the browser, as a single offline HTML file, and as a Linux desktop app, with a server for accounts and sharing. Its foundations are standalone libraries: exact rational arithmetic and indexes for SQLite, an augmented ordered map for the browser, and a conformance suite that checks both against PostgreSQL's pgmp.
λtext
Higher-order templating with type inference
λtext turns plain text files into functions: templates can take other templates as arguments, be partially applied, and be composed. A Hindley–Milner type system infers how each file is meant to be used, so mismatched templates are caught before anything is rendered.
Anabaena
L-Systems for Rust
A framework for Lindenmayer systems — the grammars behind procedurally generated plants, fractals, and patterns — supporting stochastic, context-sensitive, and parametric rules with a streaming iterator. It also powers the animation that follows your cursor on this site.
Shpadoinkle
A functional UI framework for Haskell
37 merged merge requests across the framework: Snabbdom rendering backend upgrades and FFI improvements, a double-render fix in the ParDiff backend, lazy text in the static renderer, custom HTML templates for live reload, CI for the Snowman project template, and many improvements to the documentation website.
Haskell libraries
Most of our published work is in Haskell: web routing and middleware, WebSockets, data structures, parsers, and testing utilities. Some of the most used:
nested-routes
Declarative, compositional URL routing for WAI
26.7k downloads
urlpath
A painfully simple URL combinator DSL
23.6k downloads
pred-trie
Predicative tries
19.6k downloads
markup
An abstraction for HTML-embedded content
14.4k downloads
websockets-simple
Composable WebSocket clients
11.4k downloads
sets
A duck-typed set interface for Haskell containers
10.5k downloads
cassowary-haskell
The Cassowary linear constraint solver
23 stars
dag
A well-typed directed acyclic graph
13 stars
PureScript
We've published dozens of PureScript libraries — FFI-friendly native tuples, Web Crypto bindings, WebSocket RPC, binary encodings, and type-level QuickCheck combinators — and five of them, including monad-control and monad-unlift, are part of the official PureScript package set.
Upstream contributions
Improvements we've contributed back to projects across the ecosystem:
- Stackage — 14 merged pull requests curating packages into the Haskell community’s stable package set
- PureScript package sets — 7 merged pull requests; five of our libraries are in the official set today
- purescript-arraybuffer — A redesign of the library’s typed-array and DataView API
- purescript-uri — Correct parsing of IPv4 addresses
- purescript-quickcheck — A fix for generic coarbitrary instances
- Yew — NodeRef support for yew-router’s Link component
- persistent — A bug fix for Yesod’s database layer
- saltine — Hashable and Generic instances for the Haskell libsodium bindings
- leaflet-rs — Tile layer attribution for the Rust Leaflet bindings
- asciidocr — Reporting scanning errors through Result types in a Rust AsciiDoc parser
Explore everything
Hundreds more repositories — experiments, bindings, and tools — are on our profiles.
Download and star counts as of October 2026.