The Only API

What it is

The Only API is a third-party REST API for OnlyFans and Fansly, sold to agencies and developers who manage creator accounts. It does not pay creators; it is a paid tool that automates the work around an account that already earns. The site says its 500+ documented API operations cover messaging and mass DMs, fan and subscriber management, earnings and payouts, campaigns and tracking links, webhooks, automations and data export, all under one API key. There is a free plan for 1 account, and paid accounts are billed per connected account, with a 14-day free trial. The about page says the product comes from Xcelerate Management Limited, a New Zealand-registered company, and that the team "started as agency operators managing dozens of OnlyFans accounts manually." Its co-founder and CEO is described as a former agency operator who managed 50+ OnlyFans accounts by hand, and its co-founder and CTO as an engineer with 5+ years building API infrastructure.

How earning works with it

The money still comes from OnlyFans or Fansly subscriptions, tips and PPV sales. The Only API's job is to let an agency handle more accounts with less manual work, and the site describes several kinds of workflow.

The first is messaging and fan management. Agency staff or scripts send mass DMs, manage fan lists and handle subscribers without logging into each account one by one. The comparison page names the typical jobs: mass DMs, scheduled follow-ups, PPV blasts and fan tagging.

The second is automation and data export. Users connect Make, Zapier or their own code to the API. The home page describes automations as trigger, conditions and action rules, with examples such as auto-thanking tippers, welcoming new subscribers and escalating VIPs. Webhooks send HMAC-signed events, such as new messages, posts and profile updates, to the user's own systems with automatic retries and failure alerts; Discord, Slack and Telegram endpoints are approved automatically.

The third is multi-account operation. The site says it fits agencies from 5 to 500+ creators. Each connected account sits in its own slot with its own managed session and a proxy the user supplies through the X-Proxy header, so accounts stay isolated even under one API key. Fansly accounts connect with email or username and password, with 2FA supported, or with existing session credentials, and the site says Fansly data comes back in the same response shapes as OnlyFans data.

It is not only an API. The home page shows a dashboard built for agencies, with an earnings breakdown, a live activity feed and quick stats, plus a Fans CRM that ranks every fan by spend. The free plan lists dashboard analytics among its features.

For people who work with AI assistants, the service runs a hosted MCP server, so Claude, ChatGPT, Cursor and other MCP clients can query OnlyFans and Fansly data in plain language. The site says write access through MCP is off by default and enabled per panel, and that non-GET requests through the generic OnlyFans proxy tool are off by default too. Developers get a public OpenAPI 3.1 spec, an interactive playground with ready-to-run cURL, and an llms.txt index of the docs.

On reliability, the about page argues that health checks, delivery logs, refresh status and the public OpenAPI document make performance and failures inspectable "instead of relying on an unverified speed claim." Migration help is offered by email: a user describes the workflow they want to replicate and the team maps it to endpoints, automations or no-code Make and Zapier flows. The comparison page says Slots customers get priority email support, and Enterprise customers get white-glove onboarding, a dedicated account manager and custom SLAs.

Money and rules

The Only API bills a flat monthly price per connected account, which it calls a slot, with no per-call charges. The site defines a slot as a 30-day right to keep one account connected; adding an account creates a slot charged on a prorated basis, and slots can be added and removed at any time. The Free plan covers 1 connected account and 1,000 API calls a month, no credit card required, with all 500+ operations and no feature gating. As of October 2026 the pricing page lists the Slots plan at $20 per connected account per month, falling to $15 per account once a customer has 15 or more slots, and says Stripe applies that volume tier automatically. Agencies with 50+ accounts are told to contact sales for Enterprise pricing below the volume rate.

Paid slots carry unlimited monthly API calls, with no credits and no per-call charges on any tier, the comparison page says. A 1,000 requests per minute anti-flood limit applies to every plan, and the Free plan is the only one with a monthly call cap. Paid slots start with a 14-day free trial with full access, and the pricing page says a card is never charged if the trial is canceled before it ends. Taxes, proxy services, captcha credits and self-hosting infrastructure are billed separately or supplied by the user.

There is also a self-hosted, open-source version under AGPL-3.0. The terms say it may be studied, modified, run or redistributed, including commercially, and that where the terms conflict with that license for the software, the license prevails; it grants no right to use the hosted service outside the terms. Self-hosting means running one's own infrastructure, proxies and captcha credits. The terms are governed by the laws of New Zealand.

Who it suits and who it does not

The Only API suits an agency running many OnlyFans or Fansly accounts that wants one key and one dashboard instead of separate logins, and a developer building custom tools on top of those accounts. Teams already using Make or Zapier can plug it into existing flows, and the MCP server lets non-developers ask questions of their account data through an AI assistant. The per-slot price with a volume step at 15 accounts favors growing agencies, and the free plan lets a team test before paying.

It is a weaker fit for a solo creator running one account who does not automate anything, since most of the value is in scale. Every account needs a proxy the user supplies, which adds cost and some technical work. The free plan's 1,000 calls a month is enough to test but not to run high-volume automation, so serious use means paying per slot. And a creator looking for fans, a marketplace or payouts will not find them here: this is infrastructure for accounts that already earn.