The Only API is a third-party REST API for teams building tools around OnlyFans and Fansly. It provides one documented interface for account data, messaging, earnings, fan and subscriber records, campaigns, webhooks, automations, and data exports.
What the platform covers
The public product and documentation describe more than 200 endpoints. They cover common agency workflows such as reading subscriber and transaction data, managing campaign links, reviewing messaging activity, receiving event notifications, and exporting account data.
The service also publishes an OpenAPI specification, interactive documentation, AI-readable documentation, and an MCP server. That gives engineering teams several ways to explore the API before committing to an integration.
How access and billing work
Requests use an API key. Connected creator accounts occupy subscription slots, while a free plan is available for testing with a limited monthly request allowance. Paid slots use account-based pricing rather than per-call credits, subject to the service’s request limits.
Each connected account uses its own proxy and managed session. Write actions such as sending messages are disabled by default and must be enabled for the relevant account. Those defaults are useful controls, but an integration still needs scoped keys, webhook verification, logging, retries, and an internal approval policy.
Where it fits in an agency stack
Use an API layer when your team needs creator-platform data inside its own CRM, reporting pipeline, automation service, or internal dashboard. A direct API can reduce manual exports and duplicate entry, but it does not replace clear operating rules or careful handling of account access.
Before integrating, document these decisions:
Which accounts, users, and services may read or write data.
Which events should arrive through webhooks and how failed deliveries will be retried.
How proxies, session credentials, API keys, and audit logs will be stored.
Which actions require a human approval step before execution.
Teams can review the current endpoint catalog and plan details at theonlyapi.com before designing an integration.