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59API: One Key for Claude, GPT, Gemini, DeepSeek and Kimi

Connect multiple AI providers without rebuilding your app

Testing Claude, GPT, Gemini, DeepSeek and Kimi should not require five separate integrations. With 59API, you use one API key and a shared relay endpoint to access models across these providers. Your application can keep its OpenAI-compatible client while changing the model selected for each task.

For busy developers, the benefit is practical: less credential management, simpler experiments and centralized pay-as-you-go spending. This quick-start covers a first request, model switching and the checks worth making before production.

1. Create a key and choose a model

Sign up for 59API, create an API key and check the available balance or funding requirements before sending requests. Treat this key like a production secret: keep it on your server, exclude it from source control and never embed it in browser or mobile application code.

Next, choose a model from the current catalog. For example, you could evaluate Claude Sonnet 5.5 for coding assistance and Gemini 2.5 Flash for routine extraction or summarization. Compare them on your actual workload rather than assuming either will always be the best option.

Copy the exact API model identifier from 59API. A readable catalog name is not necessarily the identifier accepted in a request. Do not guess a slug from the display name.

2. Configure the shared endpoint

The API base URL is https://api.59api.com. For OpenAI-compatible requests, use https://api.59api.com/v1 as the client base URL. Keep the endpoint, credential and model identifier configurable so you can switch environments without editing application logic.

• API key: your 59API credential, not a separate provider key.
• Client base URL: https://api.59api.com/v1 for the OpenAI-compatible interface.
• Model: the exact identifier supplied by 59API.

In your terminal, set the credential and selected model for a quick test. Use your secret manager or deployment environment for persistent configuration:

export API_KEY='YOUR_59API_KEY'; export MODEL_ID='EXACT_MODEL_ID_FROM_59API'

3. Send a minimal request

This curl request uses the OpenAI-compatible chat completions route. Replace the environment-variable placeholders above before running it:

curl --fail-with-body https://api.59api.com/v1/chat/completions -H "Authorization: Bearer $API_KEY" -H "Content-Type: application/json" -d "{\"model\":\"$MODEL_ID\",\"messages\":[{\"role\":\"user\",\"content\":\"Explain an HTTP timeout in one sentence.\"}]}"

Start with a short prompt so authentication and routing are easy to verify. If the request fails, inspect the response body. Check the credential, balance and model identifier before changing application code. Avoid repeatedly retrying configuration errors.

4. Reuse your SDK or coding tool

For an existing OpenAI SDK integration, configure its API key and base URL with the values above, then pass the selected model identifier to your request. Basic compatibility reduces migration work, but provider-specific capabilities still need testing.

59API also supports Claude Code, Codex and Gemini CLI. Follow the relevant 59API setup instructions for each tool: authentication variables, endpoint formats and configuration files are tool-specific. Do not assume an OpenAI SDK setting is automatically the correct setting for every CLI.

Before relying on an integration, test the features you need, such as streaming, tool calls, structured output or images. A successful text response does not establish support for every feature.

5. Keep costs predictable

59API is positioned among the cheapest AI API relays, with pay-as-you-go access and native, official-quality models rather than downgraded substitutes. That makes it an appealing option for developers testing several providers without maintaining separate integrations.

• Check current input and output prices for each selected model.
• Measure cost per accepted result, not just cost per request.
• Limit unnecessarily long prompts and outputs.
• Use bounded retries; repeated requests can increase spending.
• Review relay data-handling policies before sending sensitive information.

A referral rebate is also available; check its current terms before factoring it into your budget. If you want a simpler starting point for multi-model development, sign up for 59API and benchmark two models against the same small set of real tasks.

Pricing · Docs