Developers
FillFaster is a PDF form automation and e-signature platform with a REST API.
FillFaster for developers
Section titled “FillFaster for developers”Want FillFaster to talk to your CRM, backend, or automation? You are in the right place. Below you will find an interactive reference you can click through, a downloadable API description developers and tools rely on, and how-to guides for everyday tasks like tokens and webhooks.
If you are unsure where to start: open the interactive reference, or grab the JSON file when your developer (or an AI assistant) asks for the “API spec.”
Quick links (start here)
Section titled “Quick links (start here)”- Browse the API (interactive API reference) - Same endpoints FillFaster documents for partners. Handy to explore before you write code.
- Download the API description (JSON) - The full list of URLs, parameters, and responses your team can plug into tools or hand to a contractor.
- API overview for AI tools - Short page for people, plain file for AI agents: fillfaster-api-skill.md.
- Machine-readable index of these links - For teams that automate discovery; points to the JSON spec and the pages above.
Use the OpenAPI file in your HTTP client
Section titled “Use the OpenAPI file in your HTTP client”The interactive reference on this site and fillfaster-openapi.json stay the canonical contract for URLs, parameters, and responses. If you prefer to send requests from Postman, Insomnia, Bruno, or another client, use that app’s import from URL (often Import → Link) and paste the JSON link above, or download the file and import it locally if your network blocks remote specs.
Use cases & guides
Section titled “Use cases & guides”Hands-on articles for common setups:
Available guides
Section titled “Available guides”- Create and Get Your API Token - Create and manage API tokens for integrations
- Webhooks - Get notified when something happens on a form (usually nicer than asking “are we done yet?” over and over)
- Set Custom Base PDF via API - Set custom PDFs when creating submissions
- Form payments - Configure and troubleshoot payments inside forms
Working with an AI assistant (Claude Code, Cursor, etc.)
Section titled “Working with an AI assistant (Claude Code, Cursor, etc.)”Use fillfaster-api-skill.md for how FillFaster fits together, then fillfaster-openapi.json when it needs the precise request and response details. The AI agents overview on this site lists the same stable links.