# zsign.io — e-signatures — 2 of 5

Home > Browse > By type > saas > zsign.io

> Probe-verified (tier 2 of 3). Last checked 2026-09-26. 2 of 5 capability checks passed. 2 unknown.

- host: zsign.io
- url: https://zsign.io/
- category: e-signatures
- type: saas
- language: en

## Probe-verified · tier 2 of 3

Probed live on 2026-09-26 against rubric v1.2. 2 of 5 checks passed. 2 unknown.

- UNKNOWN — Markdown negotiation (`Accept: text/markdown`)
- UNKNOWN — Markdown twin at a predictable URL (`/page.md`)
- PASS — llms.txt (`/llms.txt`)
- FAIL — API catalog (`RFC 9727`)
- PASS — MCP server card answers (`/.well-known/mcp/server-card.json → tools/list`)

MCP tools (from tools/list on 2026-09-26): create_account, get_pricing, check_balance, get_referral_link, buy_credits, send_envelope, update_draft, add_document_to_draft, send_draft, create_template, list_templates, send_from_template, list_envelopes, get_envelope_status, get_signing_links, remind_envelope, correct_recipient_email, void_envelope, download_signed_document, download_certificate, get_audit_trail

## Unverified actions

Read from the page's own content, with the wording each was drawn from. Inference is kept separate from tested facts; an agent completing the action is tier 3.

- **buy** — "" → `https://zsign.io/mcp/open`
- **register** — "" → `https://zsign.io/mcp/open`

## Summary

API service providing legally binding e-signatures (ESIGN/UETA) with zero-human onboarding, prepaid credit packs, envelope sending, audit trails, and tamper-evident sealed PDFs for developers and AI agents.

## Context

18 sites in this index share the category "e-signatures"; 3 are transactional.

## How we grade

- tier 1 — **Declared**: The site says agents are welcome in its robots.txt. A permission, not a capability.
- tier 2 — **Probe-verified** (this site): We fetched the site and tested each signal ourselves. Dated, repeatable, re-checked on a schedule.
- tier 3 — **Behaviourally verified**: An agent completed the action end to end — booked, bought, submitted — and it worked.

## About this record

Known Good probes sites live and publishes what was tested and when.
Method: https://knowngood.sh/about.md · Rubric: https://knowngood.sh/benchmark

How we found this site: probe discovery. This site didn't declare agent access — we found it by checking the open web. Everything above was tested the same way, against the same rubric, on the date shown. [How we choose what to check, and how to opt out](https://knowngood.sh/bot)

## Where this sits

- saas: https://knowngood.sh/type/saas
- e-signatures: https://knowngood.sh/category/e-signatures
- Browse: https://knowngood.sh/browse
- Rubric: https://knowngood.sh/benchmark