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Open-source document signing libraries and signing servers in 2026

8 open-source projects, ranked by GitHub stars and how recently each was worked on. Core leads with 1.8k stars, ahead of DSS. 7 had code pushed in the last three months. Most common licenses: MIT (4), LGPL-2.1 (2) and Apache-2.0 (1). Commercial document signing libraries and signing servers are listed separately.

New this season

  1. 1
    Letsseal letsseal

    The open standard for proving any file is real, unaltered and sealed

    Framework or platform Experimental You are exploring file provenance and timestamping and want to try a new approach.

    ★ 377 Apache-2.0 JavaScript Active, pushed 14 days ago

All open-source document signing libraries and signing servers, ranked

Complete systems you can adopt 1

  1. 1
    SignServer CE Keyfactor

    SignServer – Open source, PKI-based signing software to sign code, documents, timestamps and more.

    Complete system Production-ready Your organisation needs central, audited code or document signing with keys kept off developer machines.

    ★ 441 LGPL-2.1 Java Active, pushed 2 months ago

Frameworks and platforms to build on 1

  1. 1
    Letsseal letsseal

    The open standard for proving any file is real, unaltered and sealed

    Framework or platform Experimental You are exploring file provenance and timestamping and want to try a new approach.

    ★ 377 Apache-2.0 JavaScript Active, pushed 14 days ago

Building blocks for your own system 5

  1. 1
    Core LibPDF-js

    A modern PDF library for TypeScript. Parse, modify, and generate PDFs with a clean, intuitive API.

    Building block Experimental You need PDF manipulation and signing in TypeScript beyond what pdf-lib offers.

    ★ 1.8k MIT TypeScript Active, pushed 7 days ago
  2. 2
    DSS esig

    Digital Signature Service : creation, extension and validation of advanced electronic signatures

    Building block Production-ready You build software that must produce or validate eIDAS-compliant signatures in the EU.

    ★ 1k LGPL-2.1 Java Active, pushed 19 days ago
  3. 3
    Node-signpdf vbuch

    Simple signing of PDFs in node.

    Building block Usable Your Node.js app must cryptographically sign generated PDFs.

    ★ 943 MIT JavaScript Active, pushed 13 days ago
  4. 4
    pyHanko MatthiasValvekens

    pyHanko: sign and stamp PDF files

    Building block Usable You need standards-compliant PDF signing or validation in Python.

    ★ 794 MIT Python Active, pushed yesterday
  5. 5
    Pdfsign digitorus

    Add/verify Advanced Electronic Signature (AES) and Qualified Electronic Signature (QES) in PDF (using pure Go)

    Building block Usable A Go service must sign or verify PDFs to eIDAS levels.

    ★ 171 BSD-2-Clause Go Active, pushed 7 days ago

Developer tools 1

  1. 1
    Pdf-sign svenssonaxel

    A tool to sign PDF files. With Linux support.

    Developer tool Usable You need to stamp a handwritten-style signature onto a PDF without a commercial app.

    ★ 164 MIT Python Slowing, pushed 5 months ago

Open-source licenses

  • Permissive: 6. Use it anywhere, including in closed products. You keep the copyright notice; Apache-2.0 also grants patent rights.
  • Weak copyleft: 2. Changes to the licensed files must be shared, but you can link them into a closed program.

Languages

Java 2, JavaScript 2, Python 2, TypeScript 1 and Go 1.

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