replacing OpenAI API
Open Source OpenAI API Alternatives
GPT-4 and LLM inference API — OpenAI API pricing: $3-60+/1M tokens. Below: 3 free,
self-hostable open source projects that cover the same ground, ranked by real GitHub adoption.
There are 3 open source OpenAI API alternatives tracked on this registry, against OpenAI API pricing of $3-60+/1M tokens. The most-adopted is Ollama with 181,161 GitHub stars under MIT, written in Go. Together the set has 377,772 stars across 3 languages and 1 licence. All 3 are free to self-host with no licence fee, and 3 of 3 received a commit in the last 90 days. 3 head-to-head OpenAI API comparisons are available.
Token pricing compounds with usage. Rate limits on all tiers. Your prompts are potentially training data. Latency and availability are out of your control.
Our top 3 OpenAI API alternatives
Ollama is a command-line tool and local server that manages open-weight language models on the machine it runs on. It ships a CLI, a REST API on port 11434, and client libraries for Python and JavaScript, so the same model can be driven from a terminal, a script, or an existing agent framework. Model execution is handled by the llama.cpp backend, and the project distributes installers for macOS, Windows and Linux alongside an official `ollama/ollama` Docker image.
MIT · Go · OpenAI API vs Ollama →
Open WebUI is a self-hosted, open-source AI interface that unifies access to local and cloud-based large language models. It runs entirely in a web browser and supports Ollama for local model hosting alongside any OpenAI-compatible API, including services like LMStudio, GroqCloud, Mistral, and OpenRouter. Built in Python, it functions as a drop-in replacement for proprietary AI platforms, giving users full control over their model infrastructure and data.
NOASSERTION · Python · OpenAI API vs Open WebUI →
LibreChat is an open-source, self-hostable chat interface designed as an enhanced ChatGPT clone. It unifies access to multiple AI models—including OpenAI, Anthropic, Google Gemini, DeepSeek, Mistral, AWS Bedrock, Azure OpenAI, and others—within a single web application. Built in TypeScript, it supports real-time streaming, multi-model switching, and advanced agent workflows while providing features like message search, artifacts, code interpreter, and secure multi-user authentication.
MIT · TypeScript · OpenAI API vs LibreChat →
last updated nightly · ranking method: github stars, live-tracked
Frequently asked questions
What is the best open source alternative to OpenAI API?
Ollama is the most-starred open source alternative to OpenAI API in this registry, with 181,161 GitHub stars. 3 alternatives are compared here in total.
Are there free alternatives to OpenAI API?
Yes. Every project listed on this page is open source and free to self-host — there is no licence fee. Some projects also sell a managed hosted version, but the self-hosted path costs nothing.
What should I look at when replacing OpenAI API?
Compare licence terms, community size (stars), primary language and release activity. A fast-moving project with a compatible licence and an active maintainer base matters more than raw star count when you are committing to a migration.