API

One request. One model API. Full usage control.

A single interface for leading AI models. Every request stays tied to the project or customer behind it.

Request path

From your application to the provider—and back.

Same path whether you authenticate with a project API key or a customer token.

01 · Authorize

Check identity and access

Validate the caller, project, customer, and allowed model before provider work begins.

02 · Route

Use the selected model

Translate the common request to the model's provider and preserve streaming output.

03 · Meter

Record reported usage

Record the tokens used and what the provider charged.

04 · Attribute

Update the right ledger

Apply usage to the account or customer and enforce the plan that authorized it.

One integration

Start with the ModelRelay Responses API.

Use the provider-neutral endpoint for new integrations. Existing OpenAI or Anthropic clients can point at the compatible endpoints instead.

Call a model
ModelRelay · POST /api/v1/responses Drop-in · OpenAI /v1/responses · Anthropic /v1/messages
curl https://api.modelrelay.ai/api/v1/responses \
-H "Authorization: Bearer $MODELRELAY_API_KEY" \
-H "Content-Type: application/json" \
-d '{"model":"claude-sonnet-5","input":"Hello"}'

Change the model. Keep everything else.

Built-in controls

Model access and usage rules travel with the request.

Approved models

Control which models each customer tier can use and designate the default explicitly.

Customer tokens

Give your backend a customer-scoped credential so requests resolve to the correct end user.

Budgets and balances

Enforce subscription limits or PAYGO balances before spending reaches the provider.

Why the gateway matters

Three systems become one request path.

ModelRelay sits in the request path, so model choice, access policy, and billing stay one system instead of three.

Direct provider integrationModelRelay
Model accessProvider-specific clientsEvery model through one API
Customer identityBuild the mappingCustomer-scoped tokens
Usage controlsBuild per providerTiers, limits, and balances
Customer billingReconcile separatelyUsage ledger plus Stripe-backed plans

Choose a model. Send a request. Keep the usage accountable.

Open to everyone. Every new account starts with $1 in credit.