How to Add E-Signatures to Your Bolt.new App

Bolt.new lets you build full-stack web apps directly in your browser. You prompt, it scaffolds, and you ship. But when your app needs to handle contracts, agreements, or any document that requires a legally binding signature, you need an e-signature API that works with how Bolt builds.

Firma.dev fits that workflow. It integrates with Bolt.new through standard patterns your app already uses, whether that's Next.js API routes, Netlify serverless functions, or Supabase Edge Functions. No special SDKs, no proprietary plugins.

Three integration paths, one outcome

Bolt.new projects can be structured in different ways depending on how you're deploying, and Firma.dev has a path for each one.

If you're building a Next.js app (the most common Bolt pattern), Firma.dev connects through server-side API routes. Your frontend collects the signer's details, sends them to your backend route, and the route calls Firma.dev to create and send the signing request. The signer gets the document, signs it, and your app knows when it's done.

If you're using a lighter setup with Netlify, Firma.dev works through serverless functions. Same result, different deployment target. And if your Bolt project already uses Supabase for auth and database, you can run Firma.dev through Edge Functions and keep everything in one infrastructure stack.

All three paths get you to the same place: a working e-signature feature in your app, usually within a few hours.

What your app gains

Once integrated, your users can send documents for signature, track completions in real time, and even sign documents directly inside your app through Firma.dev's embedded signing experience. No redirects to third-party pages, no broken user flows.

Every signature produced through Firma.dev is legally binding under ESIGN and UETA in the US, and eIDAS (SES and AdES) in Europe. That covers the vast majority of commercial signing use cases across both markets.

You also get Customer Workspaces if your app serves multiple clients. Each customer gets their own isolated environment with independant templates, signing requests, and usage tracking. Clean separation without building the multi-tenancy yourself.

Built for apps that are still growing

Legacy e-signature providers want annual contracts and per-seat pricing, which doesn't make sense when you're building something new. Firma.dev charges €0.029 (~3 cents) per envelope. No monthly minimums, no seat fees, no contracts. You pay when your users actually send documents for signing, and nothing before that.

For a Bolt.new project that's just launching, this means you can include e-signatures from day one without it showing up as a line item until people start using it.

Hand this to your developer

The full integration guide covers all three paths with code examples, deployment instructions, and webhook setup. If you're building the Bolt app yourself, the guide includes prompts you can paste directly into Bolt's AI chat. If you've got a developer on the team, they'll have it running fast.

Read the full Bolt.new integration guide on docs.firma.dev

Get started with Firma.dev for free, no credit card required.