Document signing infrastructure for the agentic economy

The problem that started everything

I was building AI agent workflows and kept hitting the same wall. The agent could draft an NDA based on a conversation, negotiate terms back and forth, and agree on final language. But then what? Copy-paste into DocuSign? Open a browser? That's not how agents work.

DocuSign needs a browser. HelloSign needs OAuth. Adobe Sign needs... well, Adobe Sign. None of them were designed for a world where the sender isn't human.

I needed a single API call that takes markdown — which every LLM outputs natively — and handles the entire signing ceremony: verification, signatures, certificates, delivery. That API didn't exist, so I built it. I wrote about the full technical journey on Dev.to.

The solution: one endpoint

Signbee is the API I wish existed. One POST request with the document content and recipient details. The recipient gets an email, signs on any device, and both parties receive a certified PDF with a SHA-256 signing certificate.

No SDK. No OAuth dance. No browser automation. No template builder. For a deep dive into how AI agents use this in practice, see How AI Agents Can Send Documents for Signature.

How it works under the hood

1. You call the API — POST to /api/v1/send with markdown or a PDF URL, plus recipient details.
2. Signbee generates the document — Markdown is converted to a clean PDF using pdf-lib (pure JavaScript, no Puppeteer). Cold starts under 500ms.
3. Sender is verified — With an API key, sender is pre-verified. Without one, sender gets an email OTP. Zero-setup entry point for any agent.
4. Recipient signs — They receive an email with a signing link. They review the document and sign on any device — phone, tablet, or desktop.
5. Both parties get the certified PDF — Every signed document includes a signing certificate with timestamps, IP addresses, both signatures, and a SHA-256 hash of the complete document for tamper detection.

Three ways to integrate

Built AI-native from day one

Traditional e-signature platforms were built when the user was always a person. Their template-based workflows require a human to set up fields, position signatures, and configure routing. Signbee was designed for a different world — one where AI agents draft, send, and sign documents autonomously.

Legal validity

Electronic signatures created through Signbee are legally binding under the ESIGN Act (United States), eIDAS Regulation (European Union), and the Electronic Communications Act 2000 (United Kingdom). Every document includes a tamper-proof SHA-256 signing certificate that serves as the audit trail.

For a developer-focused guide to e-signature compliance, see E-Signature Compliance: ESIGN, eIDAS & ECA Explained.

Who builds Signbee

Michael Beckett

Founder & Developer

Full-stack developer based in London, UK. I've spent over a decade building SaaS products and developer tools. Signbee started because I needed an e-signature API that didn't exist — one that worked for AI agents, not just humans clicking through dashboards. I wrote about the full technical build in “I Built DocuSign for AI Agents — Here's How” on Dev.to.

@mjcbeckett on X·Dev.to·Hacker News·hello@signb.ee

Part of B2BEE

Signbee is the flagship product of B2BEE Ltd (Company No. 12619479) — a product studio building tools and infrastructure for the agentic economy.

Pricing

Simple, predictable pricing. No per-seat charges, no envelope fees, no hidden costs. Start free with 5 real documents per month — no credit card, no sandbox.

For a full comparison with DocuSign, PandaDoc, and 8 other providers, see 10 Best E-Signature APIs for Developers.

Timeline

Contact

Questions, partnerships, or feedback: hello@signb.ee

For consulting or partnerships with B2BEE: Schedule a conversation →