Best Open Source Tools of May 2026

1. 1

   1. Kilo Code for VS Code

   878 upvotes

   Parallel agents, diff reviewer, and multi-model comparisons

   We've completely rebuilt Kilo Code for VS Code, built on OpenCode server. New portable core, parallel tool calls, subagent delegation, inline code review, multi-model comparisons. Get started: kilo.ai/install

   #1 on May 5, 2026
2. 2

   2. Radar

   395 upvotes

   The missing open-source Kubernetes UI

   Radar brings your Kubernetes workflows into one fast, open-source UI: real-time topology, resources, events, Helm, GitOps, live traffic flows, security & best-practice checks, image filesystem inspection, and MCP for AI agents. Run it…

   #3 on May 3, 20261 maker
3. 3

   3. Zed 1.0

   365 upvotes

   High-performance, open source, multiplayer code editor

   Fast — Written from scratch in Rust to efficiently leverage multiple CPU cores and your GPU. • Agentic — Run agents in parallel to smoothly edit files, navigate code, and run tools at native speed. • Collaborative — Chat with teammates…

   #2 on May 1, 2026zed.dev1 maker, 1 with an email
4. 4

   4. Ghost

   350 upvotes

   Open-source, self-hosted game servers

   Open-source dedicated game server platform. Spin up Minecraft, Valheim, Rust, Palworld, Enshrouded and Terraria on your own Hetzner Cloud account in seconds.

   #1 on May 9, 20261 maker
5. 5

   5. PandaProbe

   338 upvotes

   open source agent engineering platform

   PandaProbe is an open-source agent engineering platform that gives you deep observability into AI agent applications. Use it to trace, evaluate, monitor and debug your AI agents in development and production.

   #2 on May 3, 2026pandaprobe.com1 maker, 1 with an email
6. 6

   6. ModelHub

   317 upvotes

   The missing menu bar app for local LLMs on Mac.

   ModelHub is a native macOS menu bar app for developers working with local LLMs. It helps you discover models from Hugging Face, download the right local build, manage your model library, and use Hugging Face models with Ollama, MLX, LM…

   #2 on May 24, 20261 maker
7. 7

   7. Agentmemory

   310 upvotes

   Persistent memory for Claude Code, Codex & coding agents

   You can now give Hermes, Claude Code, and Codex infinite memory. Agentmemory is trending on GitHub with 5,000+ Stars. CLAUDE md dumps 22,000+ tokens into context at 240 observations agentmemory: 1,900 tokens. same observations. 92% less.…

   #2 on May 16, 20261 maker
8. 8

   8. Second Brain for AI

   282 upvotes

   Persistent memory for Claude, ChatGPT & Cursor. Free.

   Every AI conversation starts from zero. Your projects, decisions, and preferences disappear as soon as you close the chat. Second Brain fixes that. It is a self-hosted memory layer that works with Claude, ChatGPT, Cursor, and any MCP…

   #3 on May 31, 2026
9. 9

   9. Minions

   266 upvotes

   Open source mission control for Hermes agent

   Your Hermes Agent works great for one task. Try managing 20 in parallel? It's chaos. Cron jobs fail silently, tasks are blocked and you're spending more time fixing your agent than getting results. Minions gives you a single task board to…

   #4 on May 8, 20261 maker
10. 10

    10. Files SDK

    240 upvotes

    A unified storage SDK for object and blob backends

    A unified storage SDK for object and blob backends. One small, honest API. Web-standards I/O. An escape hatch when you need the native client.

    #4 on May 17, 20261 maker
11. 11

    11. Hyperswitch Prism

    239 upvotes

    Library to plug-n-switch payment processors

    Prism is a stateless payments library that connects your app to multiple payment processors. You can integrate once and point to any payment processor; add fallbacks for redundancy, switch processors based on routing rules - all by…

    #4 on May 12, 20261 maker
12. 12

    12. Warp Open-Source

    225 upvotes

    Agentic development environment built with the community

    The best, longest-lasting software is built with the people who use it, so we've opened up Warp to the community. To make this possible, Oz-managed agents do the heavy lifting (coding, planning, testing), letting community members focus…

    #7 on May 11, 20261 maker
13. 13

    13. Openstatus MCP Health Checker

    204 upvotes

    Test MCP servers like a real AI client, not just a ping

    Most monitors just send an HTTP ping. But a 200 OK is useless if the JSON-RPC handshake fails. Our tool is different because it performs a true protocol-level check, acting exactly like a real AI client. Key features: Full Handshake…

    #4 on May 30, 20261 maker
14. 14

    14. Raindrop Workshop

    187 upvotes

    Open source, free, local debugger for AI agents

    Raindrop Workshop is the first local debugger for agents. It's free, local, and open source. Your local agent traces stream, token-by-token, instantly. Another Agent like Claude Code can read them over MCP. Then Claude can write evals…

    #6 on May 14, 20261 maker
15. 15

    15. Step 3.7 Flash

    182 upvotes

    Flash-speed agents model that can see and act

    An Apache 2.0 open-weight Flash model for real-world agents. Step 3.7 Flash combines vision, coding, search, tool use, 256K context, ~11B active params, and up to 400 TPS.

    #5 on May 30, 2026
16. 16

    16. Rosentic

    180 upvotes

    Catch when coding agents break each other before merge

    Rosentic checks every PR against every other open PR before merge. When coding agents work in parallel, they break each other in ways no single-PR tool catches. Rosentic catches it. Deterministic analysis. Same scan, same result, every…

    #5 on May 3, 2026rosentic.com1 maker
17. 17

    17. Re_gent

    178 upvotes

    Version Control for AI agent Activity

    Git for your AI agent’s actions. Undo, trace, and control every step. re_gent shows what your coding agent changed, which prompt caused it, and lets you roll back agent work across files and sessions.

    #6 on May 20, 20261 maker
18. 18

    18. Pi Coding Agent

    175 upvotes

    The coding-agent harness you can make your own

    Pi is a minimal terminal coding harness. Adapt Pi to your workflows, not the other way around. Customize Pi with extensions, skills, prompt templates, and themes. Bundle them as Pi packages and share via npm or git. Pi ships with powerful…

    #7 on May 25, 2026
19. 19

    19. Memori

    168 upvotes

    Persistent memory from agent trace, not just conversation

    Memori launched its new agent-native memory infrastructure, enabling agents to create structured, long-term memory directly from agent trace — including execution paths, tool results, workflow steps, outcomes, and decision-making logic.…

    #8 on May 28, 20261 maker
20. 20

    20. TrustClaw by Composio

    150 upvotes

    Self-hosted AI agent that connects 1000+ apps on Vercel

    TrustClaw is a personal AI agent that you can self-host on Vercel with one command. Powered by Composio, it connects to 1000+ apps over OAuth, runs scheduled jobs on its own, and talks to you on the web or Telegram. It is fully…

    #9 on May 15, 2026composio.com1 maker
21. 21

    21. Standboy

    139 upvotes

    A Game Boy that wakes up while your agent works

    A Game Boy in your editor sidebar that wakes up while your AI agent works and tucks away when it stops.

    #10 on May 15, 20261 maker
22. 22

    22. Ara

    137 upvotes

    Agentic Wispr flow computer-use-agent living in your notch

    Automate everything. Bring your own LLM provider and use Codex app like Computer use for free, with several agents that can work for you autonomously.

    #9 on May 8, 20261 maker
23. 23

    23. Cline SDK

    121 upvotes

    Build coding agents with a plugin-based open-source runtime

    Cline SDK is an open-source TypeScript agent runtime with plugin architecture, native subagents, MCP support, checkpointing, cron jobs, and web fetch. For developers building custom coding agents or CLI tools.

    #11 on May 15, 2026
24. 24

    24. Compartment

    120 upvotes

    Open-source runtime for internal team software

    Compartment is a self-hosted open-source runtime for AI-built internal apps. It gives teams one place to run and share the apps, scripts, workers, and automations created with AI coding agents, on infrastructure they own. Use Cursor…

    #14 on May 28, 2026compartment.dev1 maker, 1 with an email
25. 25

    25. ShioriCode

    118 upvotes

    Open-source alternative to Codex & Claude Code

    A desktop interface for the coding-agent CLIs you already use — Codex, Claude Code, Cursor, Gemini, Kimi, and a hosted Shiori provider. Run long-running sessions with project-aware threads, stream agent activity into a readable timeline…

    #13 on May 19, 20261 maker

Junior imports every day's Product Hunt leaderboard. Each launch is filed under the first topic its makers chose, so it appears in one category only. This list takes the Open Source launches dated in May 2026 and ranks them by their upvotes. It refreshes daily.

• Best Productivity Tools214
• Best Design Tools76
• Best Developer Tools58
• Best Mac Apps46
• Best Android Apps37
• Best Marketing Tools38
• Best AI Tools41
• Best SaaS Tools27
• Best iOS Apps23
• Best APIs36
• Best Chrome Extensions28
• Best Analytics Tools27
• Best Health & Fitness Apps23
• Best Social Media Tools13
• Best Sales Tools20
• Best Fintech Tools25

• All Open Source Tools732
• Every launch in May 2026
• All best-of lists

What was the top Open Source launch of May 2026?

Kilo Code for VS Code ("Parallel agents, diff reviewer, and multi-model comparisons"), with 878 upvotes on May 5, 2026, where it finished #1 of the day.

How many Open Source Tools launched in May 2026?

67 on Product Hunt, with 8,336 upvotes between them. This list shows the 25 most upvoted.

How is this list ranked?

By Product Hunt upvotes, as recorded on launch day. Ties go to the launch with the better daily rank. Every launch is counted once, in the category its makers listed first.

How do I reach the makers of these Open Source Tools?

Each launch links to its page on Junior, with the people behind it (20 makers across this list). Junior adds their verified work emails, LinkedIn and X profiles for subscribers.