Welcoming Repositories Index Haskell Ecosystem
Top Welcoming Open-Source Haskell Repositories
Top welcoming Haskell repositories. Scored by real 90-day external PR merge rates, maintainer review turnaround speed, and first-time contributor success.
Updated daily • Thu, 15 Oct 2026 UTC
Tracked Repos
1,043
>100 stars verified
Avg Merge Rate
77%
90-day external PRs
Open GFIs
42
Beginner friendly issues
Welcoming Tier
48
S & A Tier maintainers
Ranked Haskell Repositories
Showing top 50 of 1,043 ranked repositories
| Rank | Repository | Tier | Score | Merge Rate | Good First Issues |
|---|---|---|---|---|---|
| #1 | The Software Analysis Workbench | S•Elite | 71.5 | 80.5% | 4 |
| #2 | A modern step-through debugger for GHC Haskell | A•Welcoming | 69.4 | 83.7% | 6 |
| #3 | Generate all the things (focusing on research software) | S•Elite | 69.2 | 85.2% | - |
| #4 | A Direct-to-Driver open mobility platform powering the next-generation of mobility applications in India. | A•Welcoming | 68.8 | 76.0% | - |
| #5 | Actor-based, safely typed, fast programming language. | A•Welcoming | 66.2 | 74.1% | - |
| #6 | NixOS/nixfmt1,625 The official formatter for Nix code | A•Welcoming | 65.6 | 90.0% | - |
| #7 | haskell/cabal1,745 Official upstream development repository for Cabal and cabal-install | A•Welcoming | 64.8 | 66.1% | 1 |
| #8 | The Daml smart contract language | A•Welcoming | 64.6 | 81.7% | 2 |
| #9 | Implementation of the Hydra Head protocol | A•Welcoming | 63.9 | 73.5% | 13 |
| #10 | Automatically generate Haskell bindings from C header files | A•Welcoming | 63.9 | 88.9% | - |
| #11 | A toolkit for enforcing logical specifications on neural networks | A•Welcoming | 63.7 | 82.8% | - |
| #12 | experimental solidity compiler | A•Welcoming | 63.7 | 86.7% | - |
| #13 | Main source code repository of the Tamarin prover for security protocol verification. | A•Welcoming | 63.6 | 60.8% | - |
| #14 | A fast, safe, and intuitive DataFrame library. | A•Welcoming | 63.5 | 56.0% | 4 |
| #15 | wireapp/wire-server2,781 🇪🇺 Wire back-end services | A•Welcoming | 63.5 | 65.3% | - |
| #16 | Robust, fast, intuitive plain text accounting tool with CLI, TUI and web interfaces. | A•Welcoming | 63.4 | 68.2% | - |
| #17 | Haskell to VHDL/Verilog/SystemVerilog compiler | A•Welcoming | 63.4 | 71.6% | 1 |
| #18 | Crucible is a library for symbolic simulation of imperative programs | A•Welcoming | 63.0 | 80.6% | - |
| #19 | agda/agda2,941 Agda is a dependently typed programming language / interactive theorem prover. | A•Welcoming | 62.9 | 71.1% | - |
| #20 | Assorted concrete container types | A•Welcoming | 62.7 | 83.3% | 2 |
| #21 | IntersectMBO/plutus1,632 The Plutus language implementation and tools | A•Welcoming | 62.7 | 70.5% | 1 |
| #22 | The ledger implementation and specifications of the Cardano blockchain. | A•Welcoming | 62.6 | 68.6% | - |
| #23 | Liquid Types For Haskell | A•Welcoming | 62.3 | 89.8% | - |
| #24 | fossas/fossa-cli1,523 Fast, portable and reliable dependency analysis for any codebase. Supports license & vulnerability scanning for large monoliths. Language-agnostic; integrates with 20+ build systems. | A•Welcoming | 62.0 | 58.8% | - |
| #25 | Code used throughout the Cardano eco-system | A•Welcoming | 61.9 | 81.1% | 1 |
| #26 | hadolint/hadolint12,476 Dockerfile linter, validate inline bash, written in Haskell | A•Welcoming | 61.9 | 92.9% | 1 |
| #27 | Pipe your nix-build output through the nix-output-monitor a.k.a nom to get additional information while building. | A•Welcoming | 61.8 | 81.3% | - |
| #28 | Servant is a Haskell DSL for describing, serving, querying, mocking, documenting web applications and more! | A•Welcoming | 61.7 | 80.0% | - |
| #29 | Maintenance of the pointfree Hackage package. | B•Solid | 61.7 | 100.0% | - |
| #30 | HTTP server & command-line for managing UTxOs and HD wallets in Cardano. | A•Welcoming | 61.6 | 83.6% | - |
| #31 | The core component that is used to participate in a Cardano decentralised blockchain. | A•Welcoming | 61.4 | 61.2% | - |
| #32 | digitallyinduced/ihp5,361 🔥 The fastest way to build type safe web apps. IHP is a new batteries-included web framework optimized for longterm productivity and programmer happiness | A•Welcoming | 61.3 | 76.4% | - |
| #33 | SimpleX - the first messaging network operating without user identifiers of any kind - 100% private by design! iOS, Android and desktop apps 📱! | A•Welcoming | 61.0 | 67.0% | - |
| #34 | crytic/echidna3,185 Ethereum smart contract fuzzer | A•Welcoming | 60.9 | 61.5% | - |
| #35 | Specifications of network protocols and implementations of components running these protocols which support a family of Ouroboros Consesus protocols; the diffusion layer of the Cardano Node. | A•Welcoming | 60.9 | 63.2% | - |
| #36 | Haskell implemented with combinators | A•Welcoming | 60.9 | 72.5% | - |
| #37 | An unofficial rules-compliant browser based version of Arkham Horror: The Card Game. Not produced, endorsed, or supported by, or affiliated with Fantasy Flight Games. | A•Welcoming | 60.4 | 82.8% | - |
| #38 | PostgREST/postgrest27,715 REST API for any Postgres database | A•Welcoming | 60.4 | 71.1% | - |
| #39 | dmjio/miso2,443 :ramen: A tasty Haskell web and mobile framework | A•Welcoming | 59.7 | 72.0% | - |
| #40 | rzk-lang/rzk307 An experimental proof assistant based on a type theory for synthetic ∞-categories. | A•Welcoming | 59.6 | 92.7% | - |
| #41 | GaloisInc/cryptol1,224 Cryptol: The Language of Cryptography | A•Welcoming | 59.3 | 87.5% | - |
| #42 | carp-lang/Carp6,065 A statically typed lisp, without a GC, for real-time applications. | A•Welcoming | 59.2 | 58.8% | - |
| #43 | Typed eDSL for writing UPLC /ˈpluː.tɑːk/ | A•Welcoming | 58.7 | 91.9% | 1 |
| #44 | The main concordium node implementation. | A•Welcoming | 58.7 | 58.8% | - |
| #45 | Official Haskell IDE support via the language server protocol (LSP) | A•Welcoming | 58.6 | 60.4% | - |
| #46 | Symbolic formula representation and solver interaction library | A•Welcoming | 58.4 | 87.1% | - |
| #47 | A component that follows the Cardano chain and stores blocks and transactions in PostgreSQL | A•Welcoming | 58.3 | 78.3% | - |
| #48 | jgm/pandoc46,586 Universal markup converter | A•Welcoming | 58.2 | 65.3% | - |
| #49 | tfausak/flow203 :droplet: Write more understandable Haskell. | B•Solid | 57.6 | 100.0% | - |
| #50 | A modern package index for the Haskell ecosystem | A•Welcoming | 57.6 | 87.8% | 5 |
How to Get Your Haskell PR Merged
1
Check C-Rank™ First: Pick projects with S or A tiers to avoid maintainer ghosts and slow review cycles.
2
Run Local Verification: Ensure test suites and formatting linters pass before opening a pull request.
3
Submit in Maintainer Windows: Check the repository report card to submit when maintainers are most active.
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Frequently Asked Questions: Haskell Open Source
What is the most welcoming Haskell open-source repository?
The highest-ranked Haskell repository on GetMerged is currently GaloisInc/saw-script, with a C-Rank score of 71.5/100 and a 80.5% PR merge rate.
How can I find good first issues in Haskell?
You can browse verified beginner-friendly issues in Haskell by visiting our curated Good First Issues directory at getmerged.abhishekco.de/good-first-issue/haskell.
What makes a Haskell repository ‘Super Welcoming’ on GetMerged?
A ‘Super Welcoming’ (S-Tier) Haskell repository demonstrates an external PR merge rate above 80%, a median first response time within 24 to 48 hours, active review feedback, and clear onboarding documentation.