How to Add E-Signatures to Your Mocha App

If you're building with Mocha, you can add legally binding e-signatures to your app without writing code. Firma.dev integrates with Mocha's AI-driven backend, so you describe what you want in plain English and Mocha handles the implementation.

This guide explains what the integration looks like and how to think about it. For the step-by-step walkthrough with exact prompts you can paste into Mocha, head to the Mocha integration guide on our docs.

Why Mocha + Firma.dev

Mocha lets you build full-stack apps by prompting an AI assistant. You describe features in natural language, and Mocha generates the frontend, backend functions, and database logic for you. It's one of the fastest ways to go from idea to working app.

Firma.dev fits naturally into that workflow. You store your API key in Mocha's secrets manager, give the AI a prompt describing the signing feature you want, and Mocha builds it. There's no SDK to configure, no complex authentication flow, and no package dependencies. The integration is just an API call that Mocha's backend makes on your behalf.

At €0.029 per envelope (~3 cents USD), the cost model works whether you're sending ten documents a month or ten thousand. No monthly minimums, no contracts, no per-seat fees. You pay only for what your app actually sends.

What you can build

The integration gives your Mocha app access to the full Firma.dev signing workflow. Here's what that means in practical terms:

Send documents for signature from your app. A user fills out a form in your Mocha app, your backend calls the Firma.dev API, and the recipient gets the document to sign. You could use this for client contracts, onboarding paperwork, consent forms, or anything else that needs a signature.

Embed the signing experience. Instead of sending signers to an external page, you can load the embeddable e-signature interface directly inside your Mocha app using an iframe. Your users never leave your product, and the experience feels native.

Track when documents are signed. Firma.dev sends webhook notifications when a document is completed, declined, or expires. Your Mocha app can listen for these events and react automatically, whether that means updating a database record, sending a confirmation, or triggering the next step in a workflow.

Scale to multiple customers. If your Mocha app serves different clients or organizations, Firma.dev's customer workspaces for multi-tenant e-signatures let you give each customer their own isolated signing environment with seperate templates and usage tracking.

How the integration works

The actual setup is simpler than most integrations because Mocha handles the technical parts through its AI assistant. At a high level:

1. You store your Firma.dev API key securely in Mocha's Secrets panel

2. You prompt Mocha's AI to build a signing feature, providing the API endpoint and the shape of the request

3. Mocha generates the backend function, creates the frontend form, and connects them

4. You test in preview and publish

The full integration guide includes the exact prompts to paste into Mocha for each step, including sending signing requests, handling webhooks, and embedding the signing experience. You can also add Firma.dev API details to Mocha's Custom Knowledge feature so the AI remembers how to work with Firma.dev across your entire project.

Security and compliance

Documents signed through Firma.dev are legally binding under the ESIGN Act and UETA in the United States, and support SES and Advanced Electronic Signatures (AdES) under eIDAS in Europe. All signing data is hosted on AWS infrastructure in the EU (Paris region) with CloudFront distribution from Stockholm.

Your API key stays in Mocha's encrypted secrets manager and is never exposed in frontend code. For more on how Firma.dev handles data protection, encryption, and audit trails, see our e-signature security and compliance page.

Getting started

There's no sales process or procurement cycle. You can start right now:

1. Create a free Firma.dev account at app.firma.dev

2. Set up a template with the signing fields your documents need

3. Follow the Mocha integration guide to connect everything

Firma.dev includes 25 free envelopes to test with, so you can validate the full signing flow before any cost kicks in.

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