Attest vs Documenso, DocuSeal and OpenSign

Three open-source tools and Attest

Documenso, DocuSeal and OpenSign publish their source code, mainly under the AGPL-3.0 license, run cloud services and can be installed on your own servers. Attest is a hosted service whose verification is open: its verifier is open source under the MIT license, and its evidence uses open standards. Prices below are as published on each vendor's pricing page on October 12, 2026; other details are as published on their own pages and repositories on October 11, 2026.

	Attest	Documenso (as published October 12, 2026)	DocuSeal (as published October 12, 2026)	OpenSign (as published October 12, 2026)
License	Verifier and Integrations client: MIT; the app is hosted	AGPL-3.0 (Community Edition); commercial Enterprise Edition	AGPL-3.0 with an attribution term	AGPL-3.0, per its README
Run it on your own servers	No: a hosted service	Yes. Community Edition free, listed for "Testing, Evaluation, Internal POCs"	Yes. Free edition signs with a self-signed certificate	Yes, free
Encryption, in its own words	End-to-end encrypted in the browser; Attest can't read documents	Encrypted at rest and in transit; no end-to-end mechanism described	"Encrypted in transit and at rest"; "end-to-end encryption" named on two pages, with no mechanism described	"Advanced encryption methods" for document integrity; no mechanism described for stored documents
Who signs the PDF	Each signer, with their own passkey	The platform: "The signature is applied at the platform level, not by individual signers"	The platform's certificate (trusted on cloud and paid self-hosted; self-signed on the free edition)	The platform's P12 certificate, or one you upload
Free cloud plan	2 documents, in total	5 documents a month	10 request emails a month	"Unlimited e-signatures"
Entry paid cloud plan	$5 a month for 20 documents	Individual: $25 a month, billed yearly ($300)	Pro: $20 per user a month, or $200 per user a year	Professional: $29.99 a month, or $9.99 a month on the yearly plan

Self-hosting and end-to-end encryption solve different problems

Self-hosting moves your documents from a vendor's servers to yours. That is a real benefit when policy says data must stay on your infrastructure, and the three projects are open about the trade: Documenso's security policy says "Self-hosted deployments have full control over security but also full responsibility", and DocuSeal says self-hosting gives customers "full control and responsibility over their data without third parties being involved, including DocuSeal".

None of the three describes a mechanism that keeps the server out of the documents it stores. In the cloud, Documenso describes database contents encrypted at rest, encrypted object storage and TLS 1.2 or higher in transit, and no end-to-end mechanism. DocuSeal's HIPAA page says "Documents are encrypted in transit and at rest, safeguarding protected health information end to end", and its qualified signature page says "Secure all sensitive information with end-to-end encryption", in both cases without describing a mechanism. OpenSign's FAQ says it "ensures document integrity by using advanced encryption methods", and its pages describe no encryption mechanism for stored documents. When you self-host, whoever runs the server holds the keys.

Attest takes the server out of the question instead. Every document is encrypted in the sender's browser with AES-256-GCM, its key is locked separately to each party's own key, and it is decrypted only in the parties' browsers. Attest stores your document only as ciphertext it can't read, so neither Attest nor anyone who breaks into its servers can open it. We compared 21 e-signature services in October 2026, Attest and 20 others, and Attest was the only one that end-to-end encrypts every document, for every signer, by default.

Who actually signs the PDF

For a standard signature, in all three open-source tools, the cryptographic signature on the finished PDF belongs to the platform; signer certificates come only with advanced or qualified signatures from a trust service provider, which DocuSeal offers on its EU cloud, priced per signature. Documenso's documentation is direct about it: the signature proves the document "was signed by the certificate holder (the Documenso instance)". How a PDF reader treats it depends on that certificate. Documenso explains that a certificate from a CA on the Adobe Approved Trust List shows a green check in Adobe, while a self-signed one shows a "Warning that the certificate is not from a trusted source". DocuSeal's free self-hosted edition generates a self-signed certificate, and OpenSign's documentation shows how to generate a self-signed certificate for testing.

On Attest, each signer signs. A passkey is a cryptographic key only the signer controls, unlocked with Face ID, Touch ID, Windows Hello or the device PIN. The passkey signs a statement naming the exact document, by its fingerprint, and everything that signer entered, and anyone can re-check each signature from the stored evidence with any WebAuthn library. Documenso offers passkeys too, as a way to re-authenticate before signing, on its Enterprise Edition and for signers who have a Documenso account with a passkey configured.

Open where it matters for proof

Open source lets you inspect how a service works. For a signed agreement, the part you need to inspect years later is the proof, and Attest puts it in your hands:

• The verifier is open source (MIT, on GitHub at DataHubz/attest-verifier), its build is reproducible, and each release is published with its SHA-256.
• A copy of the verifier travels inside every signed PDF, with the full evidence and the original document. Drop the PDF on it in any browser and it checks the original against what every signer signed, each signer's passkey signature and entries, Attest's anchored record of the agreement on the Horizen public blockchain, and that nothing was added after sealing; it re-makes every page you see from what was signed and compares the result byte for byte.
• Open standards only: WebAuthn, SHA-256, Merkle trees and Groth16. Each cryptographic check can be run with standard tools, such as any SHA-256 tool, any WebAuthn library and any Ethereum JSON-RPC node.

A self-hosted tool's standard proof is the PDF signature of whoever ran the server. An Attest copy's proof is each signer's own signature and a public blockchain anchor, which keep working if Attest is gone.

Price

As published October 12, 2026	Attest	Documenso	DocuSeal	OpenSign
Free	2 documents, in total	5 documents a month (cloud); Community Edition self-hosted	10 request emails a month (cloud); free self-hosted edition	Unlimited e-signatures (cloud); free self-hosted
Entry paid plan	$5 a month for 20 documents	$300 a year (Individual)	$20 per user a month, or $200 per user a year	$29.99 a month, or $9.99 a month yearly
API	Pro: $49 a month	On every plan; unlimited on Platform ($3,000 a year)	$0.20 per completed document	From Professional, with premium credits

As published on October 12, 2026. On price alone, OpenSign's free cloud plan and the free self-hosted editions cost less than Attest; running a server has its own costs in hosting, updates and security.

When an open-source tool is the better fit

• Your data must stay on your own servers, and you have the people to run, patch and secure a signing service.
• You want to change the code or embed signing in your product. Documenso notes that if you modify it and make it available over a network, the AGPL requires sharing your modified source; it sells a commercial license for other cases.
• You need high volume at low cost: OpenSign's free cloud plan advertises unlimited e-signatures, and DocuSeal's API costs $0.20 per completed document, as published on October 12, 2026.
• You need workflow features such as templates, bulk send and embedded signing, which all three offer, or payments and SMS checks, which DocuSeal offers.

Who should choose Attest

• Teams with confidential agreements who want no server, theirs or a vendor's, to be able to read them: every Attest document is end-to-end encrypted in the browser.
• Anyone who wants each signer's own signature, not a platform certificate, on the record.
• People who want open, independent verification without running infrastructure: the verifier travels inside the file.
• Small senders: 20 documents a month for $5, month to month.

Starting on Attest

Sign in with your email, set up your signing key with a passkey and a recovery phrase, upload a PDF of up to 8 MB, add your signers and place their fields. Your first 2 documents are free, in total.