Which coding tools work best with your own API endpoint
From 400+ developers: Cline and Kilo Code work best with a custom endpoint. Claude Code is just as good if the endpoint speaks Anthropic's format. Codex, Antigravity and Copilot are the hardest.
If you use your own API endpoint instead of a tool's built-in models, some coding tools make it easy and some make it painful. We asked more than 400 developers which tools they use this way and what went wrong, then grouped the tools by what they told us.
We sell API access, so we have an interest here. Our endpoint serves OpenAI Chat Completions, Anthropic Messages and OpenAI Responses, so formats are not a problem for us. This ranking is what developers reported, not a lab test.
The ranking
| Group | Tool | In one line |
|---|---|---|
| 1. Top picks | Cline | The best all-rounder. Works with almost any endpoint. |
| 1. Top picks | Kilo Code | Same ease as Cline, and you can pick the API format. |
| 2. Top picks, with a catch | Claude Code | One of the best, but only if your endpoint speaks Anthropic's format. |
| 2. Top picks, with a catch | OpenCode | Works well. Adjusting thinking or reasoning effort can be tricky. |
| 3. Weak | Codex | Needs the Responses API, which many providers lack. Feels unnatural with custom endpoints. |
| 4. Hardest | Antigravity | No official way to use your own endpoint. |
| 4. Hardest | Copilot | Custom endpoints only for chat, and only in VS Code. |
Group 1: Top picks
Cline. You choose "OpenAI Compatible" as the provider, then enter the base URL, your API key and the model ID. That is the whole setup (Cline docs). Developers called it the best option overall because it covers everything the others do, with the least friction.
Kilo Code. The setup is almost the same as Cline. It also lets you choose which API format the endpoint speaks: OpenAI Compatible, OpenAI Responses or Anthropic Messages (Kilo docs).
With both, you usually have to type the model's context window and output limit yourself, because a custom endpoint does not tell them.
Group 2: Top picks, with a catch
Claude Code. It only speaks Anthropic's Messages format. You point it at your endpoint with the ANTHROPIC_BASE_URL setting (Claude Code docs). If your endpoint serves that format, developers said it is a no-brainer: one of the best tools, and it works extremely well even with custom connectors. If your endpoint only speaks the OpenAI format, it will not work without a translating proxy in between.
OpenCode. It connects to OpenAI-compatible endpoints well. The catch, from developers: changing the thinking or reasoning effort is sometimes tricky.
Group 3: Weak
Codex. Since February 2026, Codex custom providers must use OpenAI's Responses API. The older Chat Completions option was removed (guide). Many providers do not offer the Responses API, so Codex often fails against them with errors that look like a model problem but are really a format mismatch. Developers also said the connection feels unnatural and was the roughest of all the tools when used with a custom endpoint.
Group 4: Hardest
Antigravity. We found no official way to use your own endpoint or API key. A Google forum answer says bring-your-own-key is not supported, and the only workarounds we saw were unofficial proxies.
Copilot. Developers told us it does not support custom providers out of the box, and that its tools work best with its own integrations. That has partly changed. VS Code 1.122 and newer can add a custom endpoint in Copilot Chat (setup guide), but only for chat. Inline suggestions still need a GitHub sign-in, and on Business and Enterprise plans an admin can switch the feature off (GitHub). We only checked VS Code.
What to do
- Does your endpoint speak Anthropic's Messages format? Use Claude Code.
- If not, use Cline. Kilo Code is a close second.
- Need Codex? Make sure your provider supports the Responses API, or put a translating proxy in front.
- Skip Antigravity if you need your own endpoint.