8 Best Open Assistant API Alternatives in 2026 (Open Source)
Open Assistant API — Open-source, self-hosted AI assistant API compatible with OpenAI and supporting LLMs, RAG, and tools. Open-source OpenAI Assistant API compatible service supporting multiple LLMs via One API, with RAG, web search, and local deployment
Short answer
- Closest match to Open Assistant API: Astra Assistant API.
- Most actively developed: LibreChat (1,199 commits in the last 90 days).
- Fastest growing: LibreChat (+1,618 GitHub stars in the last 30 days).
- No commit in 6+ months: Astra Assistant API, TaskingAI, workgpt and RestGPT and 1 more.
These 8 open-source tools do the same job. They are ordered by how closely they match Open Assistant API, with live GitHub data so you can see which projects are actively maintained.
| Tool | GitHub stars | Stars / 30d | Last commit |
|---|---|---|---|
| Open Assistant API(original) | 367 | +1 | 2024-12-14 |
| Astra Assistant API | 207 | 0 | 2025-08-18 |
| TaskingAI | 5.4k | +4 | 2024-10-31 |
| workgpt | 731 | 0 | 2023-06-23 |
| RestGPT | 1.4k | +2 | 2023-09-28 |
| CodeFuse-ChatBot | 1.3k | +1 | 2024-07-01 |
| DB-GPT | 20.1k | +268 | 2026-09-28 |
| LibreChat | 45.2k | +1,618 | 2026-10-01 |
| OpenAI Developers Responses API reference | 2.5k | +31 | 2026-10-02 |
1. Astra Assistant API
Drop in replacement for the OpenAI Assistants API
What sets it apart: Drop-in OpenAI Assistants API v2 replacement supporting 30+ LLM providers via LiteLLM, backed by AstraDB vector storage
Best for: openai-assistant-api-with-alternative-llms; multi-provider-assistant-apps; astradb-users
2. TaskingAI
The open source platform for AI-native application development.
What sets it apart: It combines model access, tools, RAG, assistants, and conversation state in an open-source backend designed to move agents from prototyping to deployment.
Best for: Developers building LLM-based agents; Teams needing a backend service for AI applications; Multi-model applications
3. workgpt
A GPT agent framework for invoking APIs
What sets it apart: vs LangChain / AutoGPT: TypeScript-native agent framework with first-class OpenAPI integration — any API with an OpenAPI spec becomes an LLM tool automatically, with built-in web browsing and structured output extraction
Best for: Automating multi-API workflows from natural language directives; Web scraping and structured data extraction with LLM intelligence; TypeScript developers wanting an agent framework with OpenAPI-first design
4. RestGPT
An LLM-based autonomous agent controlling real-world applications via RESTful APIs
What sets it apart: vs basic API wrappers: iterative coarse-to-fine planning combining high-level task decomposition with fine-grained API selection — addresses practical challenges of multi-step API orchestration
Best for: Automating complex multi-step REST API workflows; Research into LLM planning for API orchestration; Testing LLM capabilities against realistic API integration tasks
5. CodeFuse-ChatBot
An intelligent assistant serving the entire software development lifecycle, powered by a Multi-Agent Framework, working with DevOps Toolkits, Code&Doc Repo RAG, etc.
What sets it apart: vs GitHub Copilot/Cursor: multi-agent DevOps assistant from Ant Group with repository-level code analysis, knowledge graphs, and sandboxed execution — designed for enterprise private deployment
Best for: DevOps teams needing AI-assisted code analysis and generation; Enterprise teams wanting private, self-hosted coding assistant with RAG
6. DB-GPT
open-source agentic AI data assistant for the next generation of AI + Data products.
What sets it apart: Full-stack AI data assistant combining autonomous SQL generation, sandboxed code execution, and reusable skills in a single platform — not just a chatbot
Best for: Data teams needing natural language database querying; Organizations wanting AI-powered data analysis assistants; Teams building data-driven agent workflows
7. LibreChat
Open-source ChatGPT-like interface for multiple AI models, agents, and sandboxed code execution
What sets it apart: Most feature-complete self-hosted ChatGPT alternative — uniquely combines agents, MCP, code interpreter, image gen, and multi-user auth in one package, unlike single-provider UIs
Best for: Organizations wanting a private, self-hosted ChatGPT replacement; Teams needing multi-user AI platform with access control and audit
8. OpenAI Developers Responses API reference
OpenAPI specification for the OpenAI API
What sets it apart: The canonical machine-readable OpenAI API specification — the single source of truth for building typed clients, mock servers, and API tooling around OpenAI's services
Best for: SDK authors generating OpenAI client libraries; Developers building OpenAI API integrations with type safety
FAQ
- What are the best alternatives to Open Assistant API?
- The closest open-source alternatives to Open Assistant API are Astra Assistant API, TaskingAI and workgpt, followed by RestGPT, CodeFuse-ChatBot and DB-GPT. They are ranked by how closely they match what Open Assistant API does.
- Which Open Assistant API alternative is the most popular?
- LibreChat has the most GitHub stars among Open Assistant API alternatives, with 45,203 stars.
- Which Open Assistant API alternative is the most actively maintained?
- By recent activity, LibreChat (1,199 commits in the last 90 days) is the most actively developed alternative.