Which AI developer tools are open source?

Open-source AI developer tools

The INITE Atlas lists 232. By use, the list opens with Ollama, Keploy, OpenCode, Continue (Mission Control) and Cypress.

Offered under an open-source licence, per the pricing page; any paid tier is hosting or support.

Where each one says so

Tool	Where it says so	Price	Visits/mo
OllamaFree plan · From $20/mo	per the homepageollama.com	Free plan · From $20/mo	193k
KeployFree plan · From $19/user/mo	per the homepagekeploy.io	Free plan · From $19/user/mo	153k
OpenCodeOpen source	opencode.airead Sep 21, 2026	Open source	108k
Continue (Mission Control)Open source	continue.devread Sep 24, 2026	Open source	91.9k
CypressFree plan · From $67/mo	per the homepagecypress.io	Free plan · From $67/mo	61.2k
Nous ResearchOpen source	nousresearch.comread Sep 24, 2026	Open source	33.7k
Carbon Design SystemPrice not read	per the homepagecarbondesignsystem.com	Price not read	26.1k
SveltePrice not read	per the homepagesvelte.dev	Price not read	25.6k
Open WebUIFree plan	per the homepageopenwebui.com	Free plan	25.2k
AI SDKOpen source	ai-sdk.devread Sep 21, 2026	Open source	22.6k
HindsightFree plan	per the homepagevectorize.io	Free plan	13.2k
MedusaFrom $29/mo	per the homepagemedusajs.com	From $29/mo	11.2k
SentientOpen source	sentient.xyzread Sep 24, 2026	Open source	9.5k
TiptapFree plan · From $49/mo	per the homepagetiptap.dev	Free plan · From $49/mo	9.5k
MastraOpen source · From $250/mo	mastra.ai/pricingread Oct 20, 2026	Open source · From $250/mo	7.1k
DenoFree plan · From $20/mo	per the homepagedeno.com	Free plan · From $20/mo	6.9k
The Best API Documentation ToolFrom $10/user/mo	per the homepageredocly.com	From $10/user/mo	3.6k
Uno PlatformFree plan · From $39/user/mo	per the homepageplatform.uno	Free plan · From $39/user/mo	3.4k
AG-UIOpen source	docs.ag-ui.com/introductionread Sep 21, 2026	Open source	3.1k
ChurnkeyFrom $250/mo	per the homepagechurnkey.co	From $250/mo	2.9k
DevCycleFree plan · From $625/mo	per the homepagedevcycle.com	Free plan · From $625/mo	2.6k
OpenPetsPrice not read	per the homepageopenpets.dev	Price not read	2.6k
NocoBaseFree plan · From $800 once	per the homepagenocobase.com	Free plan · From $800 once	2.2k
DayPilotPrice not read	per the homepagedaypilot.org	Price not read	1.5k
RTKFree	per the homepagertk-ai.app	Free	1.5k

Ranked by use

Price

Figure and bar: visits/mo, estimate · year: online since

#26
Ollama
Runs open-source language models locally or in cloud, with API access for coding agents.
193k
Active
From $20/mo
2023
#31
Keploy MCP · open
Captures production traffic to generate tests and mocks, replaying them to detect regressions.
153k
Active
From $19/user/mo
2021
#42
OpenCode
Open source coding agent that generates code in terminal, IDE, or desktop app with support for multiple LLM providers.
108k
Active
Open source
2025
#48
Continue (Mission Control)
Open-source coding agent that assists developers with code generation and refactoring tasks.
91.9k
Active
Open source
#59
Cypress MCP · sign-in
Runs browser and component tests for web apps inside a real browser, with time-travel debugging and a hosted Cloud dashboard for CI results.
61.2k
Active
From $67/mo
2014
#80
Nous Research
Trains and releases open source language models with infrastructure for distributed training.
33.7k
Active
Open source
#91
Carbon Design System MCP · sign-in
Provides IBM's open-source UI components, design tokens, icons and usage guidelines for building consistent product interfaces.
26.1k
Active
1911
#92
Svelte MCP · open
Compiles HTML, CSS and JavaScript components into minimal browser code, a UI framework that does most of its work at build time.
25.6k
Active
2016
#93
Open WebUI
Self-hosted web interface for running AI models locally with data residency and access control.
25.2k
Active
Free plan
#99
AI SDK
Unified TypeScript SDK for building AI applications with streaming, multi-model support, and fallbacks.
22.6k
Active
Open source
#126
Hindsight
Persistent memory system for AI agents that learns from mistakes and improves decision-making over time.
13.2k
Active
Free plan
2024
#133
Medusa MCP · sign-in
Open-source commerce backend with modules for products, inventory, multi-warehouse stock, pricing rules and multi-region sales, customised by developers.
11.2k
Active
From $29/mo
2021
#141
Sentient
Develops open-source tools for AI agents to reason, learn, and improve through benchmarking and evaluation.
9.5k
Active
Open source
#142
Tiptap
Headless editor framework with extensions for real-time collaboration, AI agents, and document conversion.
9.5k
Active
From $49/mo
2023
#163
Mastra
TypeScript framework for building, deploying, and observing AI agents and workflows.
7.1k
Active
Open source
2024
#167
Deno
Fast, open-source JavaScript and TypeScript runtime with built-in tooling, package manager, and Node.js compatibility.
6.9k
Active
From $20/mo
2018
#204
The Best API Documentation Tool MCP · open
Renders OpenAPI definitions into hosted API reference docs and runs a mock server for them.
3.6k
Active
From $10/user/mo
2018
#212
Uno Platform MCP · open
Open-source .NET framework that builds one C# and XAML codebase into apps for Windows, iOS, Android, macOS, Linux and WebAssembly, with a live visual designer.
3.4k
Active
From $39/user/mo
2018
#221
AG-UI
Open protocol standardizing event-based communication between AI agents and user-facing applications.
3.1k
Active
Open source
#228
Churnkey MCP · sign-in
Hosted and open-source SDK that runs in-app cancellation flows, failed-payment retries and personalised retention offers for subscription businesses.
2.9k
Active
From $250/mo
#233
DevCycle MCP · sign-in
Serves feature flags from an edge network to gate releases, run A/B experiments, and roll out or revert features through OpenFeature SDKs.
2.6k
Active
From $625/mo
2011
#235
OpenPets
Installs animated desktop pets that react to your coding and integrate with development tools.
2.6k
Active
#247
NocoBase
Open source platform for building business systems with no-code interface and integrated AI agents.
2.2k
Active
From $800 once
2021
#281
DayPilot MCP · open
Provides JavaScript and framework components for calendar, scheduler, Gantt chart and event views embedded in web applications.
1.5k
Active
#282
RTK
Filters CLI output noise from AI agent context windows to reduce token usage and improve reasoning.
1.5k
Active
Free
#298
Blueprints Hub
Hosts community-contributed automation templates combining open source tools and models for developers to explore AI use cases.
1.3k
Active
Free
#309
OpenUI
Framework for building agent-driven interfaces that stream live UI components across React, Vue, Svelte, and other platforms.
1.1k
Active
From $49/mo
#314
MCP Builder
Orchestrates systems of AI agents that work together with unified state management and standardized protocols.
1.1k
Active
Open source
#326
Auto Learning Agents
Self-hosted platform for defining and running autonomous AI agents with persistent memory and learning capabilities.
901
Active
From $19.99/mo
#329
Multiplayer
Connects coding agents to production to automatically identify and fix application bugs using full-stack data.
857
Active
Open source
#330
T3 Code
Orchestrates multiple coding agents from one interface across desktop and mobile.
852
Active
Open source
#335
Shadcn Blocks
Copy-in React components for shadcn ui projects, plus full-stack Vercel AI SDK agent templates shipped as editable source code.
805
Active
#337
Memvid
Stores and retrieves knowledge in a single portable file for AI agents and search.
792
Maintained
Open source
#354
oMLX
Runs large language models locally on Mac with SSD-based KV cache for fast agent inference.
677
Open source
#364
FireCMS MCP · sign-in
Open-source admin GUI that samples Firestore collections, infers field types, and generates editable tables and forms.
617
Active
From ≈ $11/user/mo
#387
Multica
Manages coding agents as team members, assigning tasks, tracking progress, and compounding reusable skills.
517
Active
Open source
#438
Invertase
Serves markdown documentation from GitHub branches with built-in AI chat and agent-ready features.
327
Active
Open source
#442
GLM-4.5 Chat Service
Open-source large language model with 355B parameters and mixture-of-experts architecture for agentic AI applications.
318
Active
From $9/mo
#449
Sourcey MCP · open
Tests how AI agents can use vendors' software and publishes graded readiness reports and startup credit listings.
302
Active
#482
olud.ai
Indexes and compares 10,000 open-source AI projects and 350 models with daily-updated pricing and benchmarks.
236
Active
Free
#513
Manifest
Routes requests to multiple LLM providers and automatically fixes broken API calls before agents see them.
195
Active
From $19/mo
#514
code-review-graph
Builds a local graph of a codebase and serves it to AI code review tools over MCP and a CLI so they need less context.
195
Open source
#526
Agentfield
Infrastructure for deploying and managing AI agent systems with routing, execution, memory, and audit capabilities.
182
Active
Open source
2024
#555
AINativeLang
Compiles deterministic agents into portable code that runs on any system with reduced token costs.
156
Maintained
Open source
#556
Higress MCP Marketplace
Routes API requests and manages model inference across multiple LLM providers and MCP servers.
155
Active
#560
Open Agents
Runs coding agents in isolated cloud sandboxes that edit files, run shell commands and commit work to git branches.
151
Active
#562
sunpeak.ai
Builds and tests applications that run inside ChatGPT and Claude using the Model Context Protocol.
150
Active
Open source
#596
OpenLIT's Zero-code LLM Observability
Traces LLM and AI agent calls, evaluates outputs, manages prompts, and compares models using OpenTelemetry.
124
Active
Open source
2023

How we read a tool

No votes, no reviews, no vendor claims. Every week a crawler reads each tool's own site and a few public registries, and the words on the card are bands over what it read.

Use: visits to the site (estimated), installs from npm and PyPI, presence in Chrome's usage report.
Activity: the newest release on GitHub, npm or PyPI; the newest dated page on the site; open roles on a public jobs board.
Price: the vendor's own pricing page, read with the date. A figure is printed only when it is on that page.
The line and the use cases are written by us from the homepage, one tool at a time, and refused when they repeat the vendor's marketing.

How AI assistants read each site — the reading vendors ask us about — is on each tool's own visibility page.

How we read every tool → · By INITE Atlas Desk