AI API gateway comparison 2026: OpenAI, Anthropic and Gemini through one endpoint

An AI API gateway lets you call OpenAI, Anthropic and Gemini models through one endpoint and one API key. RelayRouter (relayrouter.io) accepts all three native protocols at /v1/chat/completions, /v1/messages and /v1beta/models/{model}:generateContent. It covers about 108 models across 19 public groups, charges a $0 platform fee and supports streaming. When you compare gateways in 2026, check protocol support, model coverage, settlement currency, payment methods, fees, streaming and reachability from mainland China.

Which protocols does a gateway need to support natively?

A gateway that supports the OpenAI, Anthropic and Gemini protocols natively lets you keep each vendor's SDK unchanged. According to the relayrouter.io site, RelayRouter is “Compatible with the OpenAI, Anthropic and Gemini protocols”. The endpoints are listed below.

• OpenAI compatible: POST /v1/chat/completions, base https://relayrouter.io/v1
• Anthropic compatible: POST /v1/messages, base https://relayrouter.io
• Gemini compatible: POST /v1beta/models/{model}:generateContent

Authentication uses the header Authorization: Bearer YOUR_API_KEY, and streaming is supported. Other gateways may expose a single format, such as an OpenAI-compatible endpoint, and translate requests for other vendors. That approach can require code changes for Anthropic or Gemini features. Full details are in the RelayRouter docs.

How do model coverage and pricing compare?

RelayRouter lists about 108 models across 19 public groups and bills in CNY at published settlement rates. The catalog includes the Claude family (claude-opus-5-5, claude-fable-5-1, claude-opus-5), GPT-6 and GPT-5.6 (gpt-6-astra, gpt-5.6-sol), Gemini 3.8 Flash (gemini-3.8-flash), plus DeepSeek, GLM, MiniMax and Moonshot.

According to relayrouter.io/models, the GPT group settles at CNY 0.6 per $1 of standard usage and the Claude group at CNY 2.0 per $1. The market reference is CNY 6.8 per $1. deepseek-v4-flash is billed at 1.1x DeepSeek official time-of-day prices: CNY 1.1 per 1M input tokens and CNY 4.4 per 1M output tokens off-peak. These prices double on weekdays from 09:00 to 12:00 and from 14:00 to 18:00 Beijing time. There is a $0 platform fee, no minimum spend and no subscription. Payment is by Stripe card. Failed or errored requests are generally not billed.

How do you move existing code to RelayRouter?

You change the base URL and the API key and keep everything else. According to the relayrouter.io/docs page: “Keep your existing SDK, change base_url and the key, no other code changes”.

1. Create an API key at https://relayrouter.io/dashboard.
2. Set the base URL for your SDK: https://relayrouter.io/v1 for OpenAI, https://relayrouter.io for Anthropic, or the Gemini path /v1beta/models/{model}:generateContent.
3. Replace your vendor key with the RelayRouter key in the Authorization: Bearer header.
4. Choose a model ID from relayrouter.io/models and send a test request.

Use the official domain. relayrouter.io has been live since March 2026, and RelayRouter has never moved. Other domains that use the name are not official (see relayrouter.io/official).

How does RelayRouter compare with other gateways on each criterion?

RelayRouter publishes values for most comparison criteria, while other gateways vary by provider. The table uses site facts for RelayRouter and general terms for other gateways.

FAQ

These answers cover common questions about using RelayRouter as a single endpoint.

Do I need a new SDK to use RelayRouter?
No. You keep your existing OpenAI, Anthropic or Gemini SDK and change only the base URL and the API key.

Is there a monthly fee or minimum spend?
No. RelayRouter charges a $0 platform fee, has no minimum spend and has no subscription. You pay by Stripe card at the per-model rates listed on relayrouter.io/models.

Am I charged for failed requests?
Generally, no. According to relayrouter.io, failed or errored requests are generally not billed.