# OpenAI-Compatible APIs: What They Are and Why They Matter

Markdown version of https://kymaapi.com/blog/openai-compatible-api-guide, for agents and crawlers. Same content as the HTML page.

- Generated: 2026-10-09T21:45:05.596Z
- HTML page: https://kymaapi.com/blog/openai-compatible-api-guide
- Model catalog: https://kymaapi.com/models.md
- Pricing: https://kymaapi.com/pricing.md

2026-04-12 · 2 min read

![Drop-in](/blog/openai-compatible-hero.jpg)

## What "OpenAI-Compatible" Means

An OpenAI-compatible API uses the same request format, same response format, and same SDKs as OpenAI. The only difference: the base URL and API key.

If your code works with OpenAI, it works with any compatible provider. No rewrite needed.

## Why This Matters

- **No vendor lock-in.** Switch providers without touching application code.
- **Use any SDK.** Python `openai`, JavaScript OpenAI library, LangChain, Vercel AI SDK, cURL. All work.
- **Access open-source models.** Models like DeepSeek V3, Qwen 3.6, and Gemma 4 are competitive with GPT-4 at a fraction of the cost.

## The 2-Line Migration

Moving from OpenAI to an open-source model through Kyma takes exactly 2 changes:

```python Python — Before (OpenAI)
from openai import OpenAI

client = OpenAI()  # uses api.openai.com

response = client.chat.completions.create(
    model="gpt-4o",
    messages=[{"role": "user", "content": "Hello"}],
)
```

```python Python — After (Kyma)
from openai import OpenAI

client = OpenAI(
    base_url="https://kymaapi.com/v1",  # ← change 1
    api_key="kyma-your-key",               # ← change 2
)

response = client.chat.completions.create(
    model="qwen-3.6-plus",  # open-source, GPT-4 class
    messages=[{"role": "user", "content": "Hello"}],
)
```

Same code structure. Same SDK. Same response format. Different model, different price.

## What Tools Support This

Any tool that lets you set a custom base URL works with OpenAI-compatible APIs:

| Tool | How to Configure |
|------|-----------------|
| **Cursor** | Settings → Models → Add custom model |
| **Cline** | Settings → API Provider → OpenAI Compatible |
| **Roo Code** | Settings → Provider → Custom OpenAI |
| **Claude Code** | Environment variables |
| **LangChain** | `ChatOpenAI(base_url=...)` |
| **Vercel AI SDK** | `createOpenAICompatible(...)` |
| **cURL** | Change the URL |

## Active Models, One Endpoint

Through Kyma API, you get access to Kyma's active open models from Google, Meta, Alibaba, DeepSeek, Moonshot, MiniMax, and more. All through `https://kymaapi.com/v1`.

Switch models by changing the `model` parameter. No new SDK, no new API key, no new billing account.

## Get Started

Head to [kymaapi.com](https://kymaapi.com), sign up for free-tier credit, and try it with your existing OpenAI code. The [quickstart guide](https://docs.kymaapi.com/quickstart) takes 2 minutes.