Welcome to SingleFile

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Welcome to the SingleFile API — the fastest way to automate business entity formation, EIN filing, document management, and annual report compliance across all U.S. jurisdictions.

What You Can Do

Form Business Entities

Incorporate LLCs, Corporations, and more in any U.S. state — programmatically.

File for EINs

Obtain federal Employer Identification Numbers directly through the API.

Manage Documents

Upload, search, and download formation documents and compliance records.

File Annual Reports

Stay in good standing with automated annual report filings across jurisdictions.

Getting Started in 4 Steps

 ┌──────────────┐    ┌──────────────┐    ┌──────────────┐    ┌──────────────┐
 │  1. Get Your │    │ 2. Get a     │    │ 3. Make Your │    │ 4. Build     │
 │  Credentials │───>│ Bearer Token │───>│ First Call   │───>│ Workflows    │
 └──────────────┘    └──────────────┘    └──────────────┘    └──────────────┘
   SingleFile          POST /o/token/     GET /entities        Formation,
   provides your       with client_id     to verify            EIN, Annual
   client_id &         & client_secret    everything works     Reports & more
   client_secret

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New here? Jump straight to the Quick Start to make your first API call in under 5 minutes.

Environments

Environment	Base URL	Purpose
Sandbox	`https://api.demo.singlefile.ai/external-api/v1/`	Development & testing — no real filings
Production	`https://api.app.singlefile.ai/external-api/v1/`	Live filings with state authorities

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Always develop and test against the Sandbox environment first. Sandbox requests behave identically to production but do not submit real filings.

Explore the Docs

Fundamentals

Authentication

OAuth 2.0 client credentials flow with auto-refresh patterns

Quick Start

Get a token and make your first API call in minutes

API Basics

Headers, response format, pagination, rate limits & conventions

Webhook Setup

Receive real-time notifications for order status changes

Workflow Guides

Business Entity Formation

End-to-end guide for forming LLCs, Corps, and more

EIN Filing

Automate federal tax ID applications

Document Management

Search, download, and organize compliance documents

Annual Report Filing

Maintain good standing with automated annual filings

Need Help?

API Reference

Full endpoint documentation with request/response schemas

Contact Support

Reach our team for integration help or questions