One OpenAI-compatible endpoint for GPT, Claude, Gemini and DeepSeek (Python + Node examples)

The team behind Gisoo, an OpenAI-compatible LLM gateway, detailed how a single base URL and API key can route requests to 682 models across vendors including GPT, Claude, Gemini and DeepSeek using the unmodified official openai SDKs in Python and Node. The gateway exposes chat, responses, embeddings, images, audio and video endpoints in the OpenAI format, plus an Anthropic-compatible endpoint and a remote MCP server for tools like Claude Code, Cursor and Cline. The team said the service was built for developers in Iran who cannot pay OpenAI, Anthropic or Google directly, with credit billed in local currency and an Iran-optimized mirror.

Most LLM projects end up talking to more than one vendor: GPT for one job, Claude for another, Gemini or DeepSeek when cost matters. Each vendor has its own SDK, key, billing account and rate limits. An OpenAI-compatible gateway removes most of that: one base URL, one key, and the model is just a string. This post shows the pattern with Gisoo https://gisoo.pro , the gateway we run disclosure: I'm on the team . It exposes 680+ models behind the standard OpenAI API shape, so the official openai SDKs work unchanged. The same code works with any OpenAI-compatible gateway; only the base URL and key change. curl -s https://gisoo.pro/api/v1/models | jq '.data | length' 682 curl -s https://gisoo.pro/api/v1/models \ | jq -r '.data | select .type=="chat" | .id' | head Each entry has an id , an owned by vendor and a type chat , image , audio , embedding , video , music . Directly connected models use their own name gpt-5-mini , deepseek-flash , gemini-3.6-flash ; the rest carry an openrouter/ prefix openrouter/anthropic/claude-sonnet-4.5 . python from openai import OpenAI client = OpenAI base url="https://gisoo.pro/api/v1", api key="sk-gisoo-v1-...", created in the Gisoo app question = "Explain idempotency keys in two sentences." for model in "gpt-5-mini", "gemini-3.6-flash", "deepseek-flash" : r = client.chat.completions.create model=model, messages= {"role": "user", "content": question} , print f"--- {model}\n{r.choices 0 .message.content}\n" Switching vendor is a one-word change. That makes it cheap to A/B models on your own prompts instead of trusting benchmarks. python import OpenAI from "openai"; const client = new OpenAI { baseURL: "https://gisoo.pro/api/v1", apiKey: process.env.GISOO API KEY, } ; const stream = await client.chat.completions.create { model: "openrouter/anthropic/claude-sonnet-4.5", messages: { role: "user", content: "Write a haiku about retries." } , stream: true, } ; for await const chunk of stream { process.stdout.write chunk.choices 0 ?.delta?.content ?? "" ; } Streaming is plain SSE in the OpenAI format, so existing UI code Vercel AI SDK, LangChain, LiteLLM clients keeps working. Because every model sits behind the same endpoint, fallback is a loop, not three SDKs: python from openai import OpenAI, APIError client = OpenAI base url="https://gisoo.pro/api/v1", api key="sk-gisoo-v1-..." def ask messages, models= "deepseek-flash", "gemini-3.6-flash", "gpt-5-mini" : last = None for m in models: try: return m, client.chat.completions.create model=m, messages=messages, timeout=60 except APIError as e: last = e vendor busy or refused: try the next one raise last model, r = ask {"role": "user", "content": "Summarise RFC 9110 in one line."} print model, r.choices 0 .message.content Order the list cheapest-first and you only pay for the expensive model when the cheap one fails. The same key covers the other OpenAI endpoints: | Task | Endpoint | |---|---| | Chat / tools / JSON output | POST /chat/completions , POST /responses | | Embeddings | POST /embeddings | | Images | POST /images/generations | | Speech-to-text / text-to-speech | POST /audio/transcriptions , POST /audio/speech | | Video | POST /videos | There is also an Anthropic-compatible endpoint https://gisoo.pro/api for tools that only speak the Anthropic Messages API, and a remote MCP server https://gisoo.pro/api/mcp for Claude Code, Cursor and Cline. Gisoo started for developers and teams in Iran, who can't pay OpenAI, Anthropic or Google directly: credit is paid in local currency, and there is an Iran-optimised mirror at ir.gisoo.pro . The API itself is the standard one, so the code above runs from anywhere. Docs Persian, code is universal : https://gisoo.pro/docs https://gisoo.pro/docs . Questions and corrections are welcome in the comments.