8 Best Astra Assistant API Alternatives in 2026 (Open Source)
Astra Assistant API — Drop in replacement for the OpenAI Assistants API . Drop-in OpenAI Assistants API v2 replacement supporting 30+ LLM providers via LiteLLM, backed by AstraDB vector storage
Short answer
- Closest match to Astra Assistant API: Open Assistant API.
- Most actively developed: LiteLLM (13,191 commits in the last 90 days).
- Fastest growing: Open WebUI (+3,942 GitHub stars in the last 30 days).
- No commit in 6+ months: Open Assistant API.
These 8 open-source tools do the same job. They are ordered by how closely they match Astra Assistant API, with live GitHub data so you can see which projects are actively maintained.
| Tool | GitHub stars | Stars / 30d | Last commit |
|---|---|---|---|
| Astra Assistant API(original) | 207 | 0 | 2025-08-18 |
| Open Assistant API | 367 | +1 | 2024-12-14 |
| LiteLLM | 60.0k | +2,991 | 2026-10-02 |
| OpenLLM | 12.6k | +53 | 2026-05-29 |
| Ollama | 182.1k | +2,499 | 2026-10-02 |
| LibreChat | 45.2k | +1,618 | 2026-10-01 |
| private-gpt | 57.6k | +57 | 2026-09-21 |
| Open WebUI | 153.8k | +3,942 | 2026-09-21 |
| NadirClaw | 655 | +46 | 2026-10-01 |
1. Open Assistant API
Open-source, self-hosted AI assistant API compatible with OpenAI and supporting LLMs, RAG, and tools
What sets it apart: Open-source OpenAI Assistant API compatible service supporting multiple LLMs via One API, with RAG, web search, and local deployment
Best for: self-hosted-openai-assistant-alternative; multi-llm-assistant-apps; enterprise-local-deployment
2. LiteLLM
Open-source Python SDK and AI gateway for calling 100+ LLMs through a unified OpenAI-compatible interface
What sets it apart: Unlike OpenRouter (hosted-only routing), LiteLLM is self-hostable and provides a full gateway with per-user spend tracking, virtual keys, and A2A/MCP protocol support — making it the enterprise LLM traffic controller
Best for: ML platform teams managing multi-provider LLM access with centralized cost tracking and auth; Developers switching between LLM providers without changing application code
3. OpenLLM
Run any open-source LLMs, such as DeepSeek and Llama, as OpenAI compatible API endpoint in the cloud.
What sets it apart: Unlike Ollama which focuses on local/desktop usage, OpenLLM bridges local development and cloud production through unified BentoML tooling — providing the same CLI workflow from laptop to Kubernetes cluster with OpenAI API compatibility
Best for: Teams wanting the fastest path from model selection to OpenAI-compatible API endpoint; DevOps engineers deploying open-source LLMs to production with Docker/Kubernetes
4. Ollama
Get up and running with Kimi-K2.5, GLM-5, MiniMax, DeepSeek, gpt-oss, Qwen, Gemma and other models.
What sets it apart: Unlike vLLM (production server focus) or LM Studio (GUI-first), Ollama is the simplest CLI-first tool for running local LLMs with one-command setup, an OpenAI-compatible API, and the largest ecosystem of 100+ community integrations.
Best for: Developers who want to run open-source LLMs locally with zero configuration; Privacy-sensitive use cases requiring fully offline LLM inference
5. 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
6. private-gpt
Interact with your documents using the power of GPT, 100% privately, no data leaks
What sets it apart: vs LocalGPT / other private RAG: production-ready OpenAI-compatible API with LlamaIndex backend, dependency injection architecture, and enterprise upgrade path via Zylon — canonical repo (zylon-ai/private-gpt) for PrivateGPT
Best for: Regulated industries needing fully private document Q&A (healthcare, legal, finance); Teams wanting an OpenAI-compatible API for private RAG; Developers building private AI apps with production-ready primitives
7. Open WebUI
User-friendly AI Interface (Supports Ollama, OpenAI API, ...)
What sets it apart: Unlike LM Studio (desktop-only, personal use), Open WebUI is a full multi-user platform with RAG, RBAC, SCIM provisioning, 9 vector DBs, and Google Drive/OneDrive integration — the most feature-complete self-hosted ChatGPT alternative
Best for: Teams wanting a self-hosted ChatGPT alternative with full data control and Ollama integration; Organizations needing enterprise-grade AI platform with LDAP/SCIM/SSO and multiple vector DB backends
8. NadirClaw
Open-source LLM router and cost optimizer with an OpenAI-compatible proxy
What sets it apart: Local-first LLM cost optimizer — classifies prompt complexity in 10ms and routes simple requests to 10-20x cheaper models, with no third-party proxy or middleman
Best for: Teams spending heavily on LLM APIs wanting 40-70% cost reduction; AI coding assistants (Claude Code, Cursor) with mixed complexity prompts; Budget-conscious developers using multiple LLM providers
FAQ
- What are the best alternatives to Astra Assistant API?
- The closest open-source alternatives to Astra Assistant API are Open Assistant API, LiteLLM and OpenLLM, followed by Ollama, LibreChat and private-gpt. They are ranked by how closely they match what Astra Assistant API does.
- Which Astra Assistant API alternative is the most popular?
- Ollama has the most GitHub stars among Astra Assistant API alternatives, with 182,051 stars.
- Which Astra Assistant API alternative is the most actively maintained?
- By recent activity, LiteLLM (13,191 commits in the last 90 days) is the most actively developed alternative.