Base URL Errors: Check Protocol, Path, and Endpoint
A practical sequence for checking a Base URL: protocol, domain, API version, endpoint, and client settings, with a short test after each change.
If you have already created an API key but your client returns 401, 404, 405, model not found, or opens a sign-in page, do not change the key, model, and address at the same time. First identify the contract your client expects—OpenAI-compatible or Anthropic-compatible—then check the address layer by layer: https → domain → base path → endpoint. Send one short request after every change. That makes it clear where the configuration stopped matching.
For BetterToken, OpenAI-compatible clients use the base URL https://www.bettertoken.ai/v1%60.?utm_source=blog&utm_medium=organic_content&utm_campaign=SEO-022&utm_content=base-url-oshibka-kak-proverit-put-i-protokol Claude Code uses the Anthropic-compatible base URL https://bettertoken.ai` and adds the required path itself. These are not interchangeable versions of the same string. Confirm the current value and tool-specific limits in the BetterToken documentation.
Separate a Base URL from a full request URL
A Base URL is the address you put into a provider field or a client configuration file. A full request URL is what you get after a library or CLI adds the resource path.
If you write a raw Anthropic Messages request yourself, the full path is https://www.bettertoken.ai/v1/messages%60.?utm_source=blog&utm_medium=organic_content&utm_campaign=SEO-022&utm_content=base-url-oshibka-kak-proverit-put-i-protokol That is not the value for Claude Code's Base URL field. With an OpenAI-compatible client, the base address normally ends in /v1` and the client adds the specific endpoint. This distinction is documented in the setup guides for Claude Code and Codex, checked on August 15, 2026.
Check five things in this order
Run these checks in sequence. After each one, repeat the same small request so that several causes do not get mixed into one result.
- Identify the protocol the client expects.
- Enter only the matching Base URL, without an endpoint.
- Confirm that
/v1appears exactly once in the request URL. - Run a minimal request without streaming or tools.
- Restart the client completely and repeat the test.
1. Check the protocol, not the model name
Look at the integration type in the tool itself. Codex, Cursor, Cline, OpenCode, and many other clients use an OpenAI-compatible configuration. Claude Code uses an Anthropic-compatible contract. If a client expects one format and receives the other, switching models will not fix the error: the server and client need different fields and paths.
Do not infer the protocol from a model name. Open the Docs page for your exact tool and find its provider, API key, and Base URL section.
2. Compare the base address without an extra path
For an OpenAI-compatible configuration, use the address in the tool documentation:
For Claude Code, use the base address without /v1 or /messages:
A common failure starts when a full URL from a curl example is pasted into a GUI Base URL field. The client then appends its own endpoint and creates a route that does not exist. If the field is named base_url, endpoint base, or API base, it usually should not include a resource name.
3. Check who owns the /v1 version prefix
The API version must appear exactly once. In BetterToken's OpenAI-compatible configuration, it is already included in the Base URL. If your SDK lets you set a version prefix separately, do not add a second /v1 unless the SDK documentation explicitly requires it.
You can usually spot this in logs: .../v1/v1/... nearly always means the URL was joined incorrectly. Conversely, leaving /v1 out of an OpenAI-compatible request can lead to a 404 or HTML instead of JSON.
4. Test the endpoint with a minimal request
Before enabling streaming, tools, or a long context, make one short request through the same client. For a raw OpenAI-compatible request, the endpoint is the resource after the Base URL; for Anthropic Messages it is /v1/messages.
Keep the test small and safe: use one short prompt, the current model ID from the Setup panel or model plaza, and your own API key. Do not put a key into an issue, screenshot, or command you plan to share. If the response returns JSON with a successful status, model, and usage, the address layer is working; only then should you investigate limits, model selection, or task parameters.
5. Restart the client after changing configuration
Many CLIs and desktop apps read environment variables and configuration only at startup. Saving a file is not enough: stop the process, open a fresh terminal or restart the app, then repeat the same small test. Otherwise you may be testing the old Base URL while looking at the new one in your editor.
How to read common responses
A 401 does not always mean the address is wrong, and a 404 does not always mean a model is unavailable. That is why the order matters: URL first, authentication second, model third, and advanced features last.
Quick paths for Codex and Claude Code
For Codex, use an OpenAI-compatible provider and follow the current Codex setup guide: Base URL `https://www.bettertoken.ai/v1%60,?utm_source=blog&utm_medium=organic_content&utm_campaign=SEO-022&utm_content=base-url-oshibka-kak-proverit-put-i-protokol your BetterToken API key, and a current model ID. Restart Codex, then run a small read-only request in a test directory. In the Dashboard, check the request time, status, model, and token usage; the Dashboard exposes those fields but does not promise storage of the full prompt or response text.
For Claude Code, follow the Claude Code setup guide: use the Anthropic-compatible Base URL https://bettertoken.ai, your own API key, and the model named in the current guide. Do not carry over the OpenAI /v1 path or add /messages manually. After restarting, run one small request before enabling tools or MCP.
Avoid these debugging traps
- Do not change the Base URL, API key, and model ID in one step; you will lose the cause of the error.
- Do not use one address for every tool: the client protocol, not a familiar URL pattern, decides the configuration.
- Do not copy a path from an old guide without checking its date and the page for your exact tool.
- Do not test a first configuration change in a production repository with write access. Use an empty test directory and a read-only task.
- Do not send a full key to support. A status code, time, tool name, and redacted request URL are enough to start troubleshooting.
Next step
Open the BetterToken Docs for your tool, create your own BetterToken API key, copy only the current Base URL for the selected protocol, and run a short test. Once it succeeds, use the Dashboard to verify status, model, and token usage—it is more reliable than treating a saved configuration form as proof that the client is using the new address.