SignThis: the facts, the limits and how to test it

What it does

1. A sender uploads a PDF, places the fields (signature, initials, date, name, email, company, title and others) and adds the signers, in a set order if needed.
2. Each signer gets a personal email link and signs on a phone or a computer. No account and nothing to install. The sender can require an access code, and reminders go out automatically.
3. When the last person signs, the PDF is sealed with a digital signature (PAdES) and an RFC 3161 trusted timestamp. Everyone receives the sealed copy and an audit certificate.
4. Anyone can check a completed PDF: in a PDF reader's signature panel, or on the verify page, which compares the file's fingerprint in the browser without uploading the file.

Two free tools need no account: the signature generator and the verify page.

Plans and limits

• An envelope is one document sent for signatures, whatever the number of signers.
• Every plan includes multiple signers, signing order, automatic reminders, access codes, sealed PDFs and audit certificates.
• Single sign-on works with Google Workspace and Microsoft Entra. Business plans also have workspace roles, session controls and a workspace audit log.
• The free allowance is 5 documents in the first 40 days. Signing a document someone sends you is free and needs no account.

The live prices are on the pricing section of the home page. A dated comparison with DocuSign's published prices is on the comparison page.

Security and evidence

• Sealed and timestamped. Completed PDFs carry a PAdES digital signature and an RFC 3161 timestamp. A change to the file afterwards shows the seal as broken.
• Hash-chained audit trail. Each step is recorded with the SHA-256 hash of the entry before it, and the head of the chain is printed on the audit certificate.
• Encrypted before storage. Documents, signatures, field values, names, email addresses and audit details are encrypted with AES-256-GCM. Each document has its own keys.
• Verification without upload. The verify page computes a PDF's fingerprint in the browser and sends only the fingerprint.
• No advertising trackers. The site has no advertising cookies, third-party analytics trackers or tracking pixels in emails.

The design, including what it does not protect against, is described on the Security page and in How SignThis seals a signed document.

For developers

• REST API (v1): upload and send documents, create drafts from templates, read signing status, and download the sealed PDF and certificate.
• Signed webhooks: a signed notice to your endpoint when a document is sent, viewed, signed, completed, declined, cancelled or expired.
• MCP server: AI assistants can list documents and check signing status. Creating drafts, sending and reminding are separate tools that work only when the key's scopes allow them.
• Keys: scoped to read, write or send, tied to one workspace, and expiring after 90 days unless set otherwise.

These are included from the Professional plan at $25 a month and on every business plan.

What SignThis does not have

A fair review should say these too.

• Online notarization.
• Identity-document or knowledge-based identity checks. A signer is identified by the personal link sent to their email address, and by an access code if the sender sets one.
• Contract lifecycle management, document generation or redlining.
• A catalog of ready-made integrations with other products. Connections go through the API, webhooks and MCP.
• Native mobile apps. It runs in the browser on phones and computers.
• Uploads in formats other than PDF.
• An independent penetration test: none has been done yet.
• A HIPAA business associate agreement: not available today.

How to test it

1. Create a free account. No payment card is asked for.
2. Upload any PDF, place a signature field and send it to an address you can open, such as a second mailbox of your own.
3. Open the email on a phone and sign. Note that no account is asked for.
4. Download the sealed PDF and the audit certificate from the completed document.
5. Open the PDF in Adobe Acrobat Reader and look at the signature panel. Then drop it on the verify page.
6. Change one byte of the file, or re-save it from an editor, and check it again. The seal should show as broken and the fingerprint should no longer match.

The method in steps 5 and 6 works for any signed PDF, from any service. It is explained in How to check whether a signed PDF has been altered.

If your review needs a feature that is only on a paid plan, write to support@signthis.pro from your publication's address and say which one.

Describing SignThis

• Name: SignThis (one word, capital S and T). The site is signthis.pro.
• Category: electronic signature software.
• One line: SignThis sends PDFs for e-signature. Signers need no account, and every completed document is sealed, timestamped and verifiable by anyone.
• Operated by: BESTAPPS LLC, in the United States.
• Images: the social card and the app icon may be used in coverage of SignThis.

Corrections

If something on this page is wrong or out of date, or a claim does not hold up when you test it, write to support@signthis.pro. This page describes the service as it works on the date above. It is a description, not a commitment, and the Terms govern the service.