Open Source Projects to Contribute To as a Tools Developer

If you build developer tools, the best open source projects to contribute to are other developer tools: linters, editors, terminals, test runners and API clients, where your fixes land in software thousands of developers use every day. Ten that had open beginner-labeled issues when we checked GitHub on October 11, 2026: rust-clippy, Neovim, Helix, Mermaid, k6, Bruno, Excalidraw, VS Code, Nushell and Kubernetes. Below is what each needs, how to find a first issue, and the rules that changed in 2026 for AI-assisted pull requests and Hacktoberfest.

The 10 projects at a glance

Issue counts are open issues with each project's beginner label on October 11, 2026. They change daily, so treat them as a sign of how welcoming a project is, not a promise.

Project	What it is	Language	Beginner label	Open beginner issues
rust-clippy	Rust's official linter	Rust	good first issue	100+
Neovim	Extensible Vim-based editor	C, Lua, Vim script	complexity:low	45
Mermaid	Diagrams from text	TypeScript	Good first issue!	53
Excalidraw	Whiteboard and diagram editor	TypeScript	good first issue	26
Helix	Modal terminal editor	Rust	E-easy	21
VS Code	Code editor	TypeScript	good first issue	18
Bruno	Git-friendly API client	JavaScript	good first issue	14
k6	Load testing tool	Go	good first issue	11
Nushell	Structured-data shell	Rust	good first issue	9
Kubernetes	Container orchestration	Go	good first issue	7

Several famous tools projects (ESLint, Prettier, Vite, Vitest, Jest, Ruff and uv among them) had zero open good first issue issues that day. Easy issues in popular repos get claimed within hours. Those projects still welcome contributions, but you'll usually start with a bug you hit yourself, a docs fix, or a help wanted issue.

1. rust-clippy

Clippy is the Rust linter that ships with the toolchain, and it is the most beginner-friendly big project on this list. Each lint is a small, self-contained piece of code with UI tests, so a first PR is often "add a lint" or "fix a false positive". The contributing guide explains the dev setup, and you claim an issue by commenting @rustbot claim. You'll learn how compiler lints work, which transfers directly to building your own static analysis tools.

2. Neovim

Neovim is a good place to learn editor internals, the Lua plugin API, and LSP client work. It doesn't use good first issue; filter by complexity:low instead. Two rules from its CONTRIBUTING.md worth knowing before you start: don't ask to be assigned, just open a reasonably complete PR; and AI-assisted contributions are allowed only if you have checked and understood the generated code yourself.

3. Mermaid

Mermaid turns text into diagrams and is embedded in GitHub, GitLab, Notion and many docs tools. Work ranges from parser fixes to rendering bugs to docs, which makes it friendly to TypeScript developers who haven't touched a parser before. The repo's main branch is develop, and the full guide lives in the Mermaid contributing docs.

4. Excalidraw

Excalidraw is a React and TypeScript canvas app with a published npm package that other tools embed. Good first issues are typically UI bugs, keyboard shortcuts or export fixes, and you can see your change working in a browser within minutes. Start with the contributing docs.

5. Helix

Helix is a Rust modal editor with built-in LSP and tree-sitter. A classic first contribution is adding or improving language support, which mostly means tree-sitter queries and config, as its contributing guide points out. Filter issues by E-easy.

6. VS Code

The world's most used editor has a huge issue tracker but only a handful of beginner issues at any time. Read the How to Contribute wiki page first: it covers building from source, which repo an issue belongs to (VS Code spans many repos), and the Microsoft Contributor License Agreement that a bot asks you to sign on your first PR. Built-in extensions, such as language features, are often easier to contribute to than the core.

7. Bruno

Bruno is an offline, open source API client that stores collections as plain files in your Git repo. It's an Electron and React app, so web developers can contribute without learning a new stack, and it's a direct way to improve a tool you might already use as a Postman alternative. See contributing.md.

8. k6

Grafana's k6 is a load testing tool written in Go that runs JavaScript test scripts. Contributions teach you about performance testing, JavaScript runtimes embedded in Go, and metrics output. Its contributing guide asks you to discuss bigger changes in an issue first and to sign a CLA through cla-assistant.io.

9. Nushell

Nushell is a shell where commands pass structured tables instead of text. Many first issues are about a single command (a flag, an error message, a type), so the scope is small even though the project is ambitious. Build instructions are in its CONTRIBUTING.md.

10. Kubernetes

Kubernetes is the largest project here and has the most structured onboarding: special interest groups (SIGs), a contributor guide, and a required CNCF CLA before any PR can merge. Code issues labeled good first issue are rare and go fast. Documentation, test flakes, and SIG-specific tooling are realistic first steps. Expect slower reviews than on the smaller projects above.

How to find a good first issue in any project

1. Search GitHub directly. This query lists beginner issues nobody is working on yet:

   is:issue is:open label:"good first issue" no:assignee language:TypeScript
   

   GitHub also surfaces approachable issues on each repo's /contribute page, for example github.com/excalidraw/excalidraw/contribute. Projects that apply the good first issue label are more likely to show up there (GitHub Docs).

2. Check the project's own label. Not everyone uses good first issue: Neovim uses complexity:low, Helix uses E-easy, Biome uses S-Good first issue. Look at the repo's labels page before concluding there's nothing to do.

3. Use a curated list. Good First Issue, Up For Grabs and CodeTriage aggregate beginner-friendly issues across projects. For your very first pull request ever, the first-contributions repo walks you through fork, branch, commit and PR.

4. Fix something you hit. The best first contribution is often a bug in a tool you use daily. You already have a reproduction, which is half the work.

How to get your first PR merged

1. Comment before coding. Say you'd like to work on the issue and briefly how. Some projects assign issues (Clippy uses @rustbot claim); others, like Neovim, prefer you just send the PR.
2. Read CONTRIBUTING.md and run the test suite locally before opening the PR. Most rejections are about missing tests, formatting, or the wrong branch.
3. Sign the CLA or DCO if the project needs one. VS Code, Kubernetes and k6 require CLAs; a bot comments on your PR with a link.
4. Keep the PR small. One issue, one PR, with a description that links the issue and explains how you tested.
5. Respond to review within a few days, and don't take change requests personally. Maintainers are reviewing in their spare time.

AI-assisted contributions in 2026

Most projects now accept PRs written with AI help, but maintainers are tired of low-effort generated PRs. Neovim, for example, requires that you've reviewed and verified any AI-generated code yourself. Hacktoberfest also changed for this reason: as of 2026, pull requests no longer count toward Hacktoberfest rewards, which now come from stickers earned at in-person Fests and online events (Hacktoberfest). The practical rule: you must be able to explain every line of your PR. If you use an agent to draft code, run the tests, read the diff, and disclose AI use when the project asks.

FAQ

What are the best open source projects to contribute to as a beginner?

Pick active projects that label beginner issues and review PRs quickly. On October 11, 2026, rust-clippy, Mermaid, Neovim, Excalidraw and Helix each had 20 or more open beginner-labeled issues. Smaller, focused tools usually review faster than giant projects like Kubernetes.

How do I find open source projects to contribute to on GitHub?

Search is:issue is:open label:"good first issue" no:assignee with a language: filter, check a repo's /contribute page, or browse goodfirstissue.dev and up-for-grabs.net. Also check each project's own beginner label, since many don't use good first issue.

Do I need to be an expert to contribute?

No. Documentation fixes, reproductions for bug reports, tests and small bug fixes are all real contributions, and they're how most maintainers started. You do need to read the contributing guide and run the tests.

Does Hacktoberfest still count pull requests in 2026?

No. For 2026, Hacktoberfest rewards are based on stickers from Fests and online activities, not on merged pull requests. Contributing to open source in October still counts for your own learning and portfolio, just not for swag.

Can I use AI tools to write my open source contributions?

Usually yes, but check the project's policy first. Projects such as Neovim accept AI-assisted work only when you've personally verified it. Never submit code you can't explain or haven't tested.

Want more? Browse open source developer tools launched on DevHunt, or read about community-built open source tools.