License & Deployment Mix: 5 tools – 5 OSS, 0 SaaS. (OSS and SaaS counts can overlap when an open-source tool also offers a vendor-hosted edition.)
What Are PDF Processing Tools?
PDF processing tools provide web-based or API-driven operations on PDF documents: merging, splitting, converting, compressing, signing, OCR, watermarking, and more. Unlike a Document Management System (DMS) that organizes and stores documents, PDF tools focus on transforming documents – they are utilities, not archives.
Key capabilities:
- Merge / split – combine multiple PDFs or extract pages
- Convert – HTML/Office/images to PDF and back
- OCR – add searchable text layers to scanned PDFs
- Compress – reduce file size for storage or email
- Sign – add digital or visual signatures
- Watermark – overlay text or images
- Redact – permanently remove sensitive content
- Batch processing – apply operations to many files at once
- Form handling – fill, flatten, or extract form data
The information on these pages was researched by a combination of human review and large language models. To suggest an addition or correction, please contact us. Prepared by Rhodium Systems Inc., author of the ResorsIT platform — a unified IT operations management platform for IT teams and MSPs that integrates a curated suite of open-source, commercial, and SaaS applications into a single system with shared identity, single sign-on, access control, and a common audit trail. Use this catalogue only as a starting point for your own research, and review any tool carefully against your own requirements before relying on it. Catalogue data version 2026.197.
Comparison
SSO / OIDC Comparison
OIDC is the preferred SSO protocol.
| Tool | OIDC | SAML | LDAP | Authentik Notes |
|---|---|---|---|---|
| Stirling-PDF | Pro* | No | No | Free: reverse-proxy auth; Pro: native OIDC |
| BentoPDF | No | No | No | Reverse-proxy auth only (static app) |
| Gotenberg | N/A | N/A | N/A | API service; basic auth or network ACL |
| SignaturePDF | No | No | No | Reverse-proxy auth only |
* = requires commercial Pro tier
Best SSO support: Stirling-PDF Pro (native OIDC); all others rely on reverse-proxy authentication via Traefik + Authentik forward-auth.
Gotenberg: SSO is not applicable – it is an API-only service with no user interface.
API Comparison
| Tool | API Type | Auth | Webhooks | Batch |
|---|---|---|---|---|
| Stirling-PDF | REST | API key / session | No | Yes |
| BentoPDF | None | N/A | No | No |
| Gotenberg | REST | Basic auth | Yes | Yes |
| SignaturePDF | None | N/A | No | No |
Best API: Gotenberg (purpose-built API with webhook support); Stirling-PDF (comprehensive REST API covering all 60+ operations).
No API: BentoPDF (client-side only) and SignaturePDF (browser-only).
Feature Matrix
| Feature | Stirling-PDF | BentoPDF | Gotenberg | SignaturePDF |
|---|---|---|---|---|
| Merge | Yes | Yes | Yes | No |
| Split | Yes | Yes | No | No |
| Convert to PDF | Yes | Images | Yes | No |
| Convert from PDF | Yes | Images | No | No |
| OCR | Yes | No | No | No |
| Sign | Yes | Yes | No | Yes |
| Compress | Yes | Yes | No | No |
| Watermark | Yes | Yes | No | No |
| Redact | Yes | No | No | No |
| Encrypt/Decrypt | Yes | Yes | No | No |
| Form handling | Yes | Flatten | No | No |
| Batch processing | Yes | No | Yes | No |
| Page operations | Yes | Yes | No | Basic |
Most complete: Stirling-PDF (60+ operations).
Conversion specialist: Gotenberg (Chromium + LibreOffice; best for automated pipelines).
Privacy-first: BentoPDF (all processing in browser via WASM; no server upload).
Signing-only: SignaturePDF (minimal scope).
Processing Model
| Tool | Model | Privacy | Large Files |
|---|---|---|---|
| Stirling-PDF | Server-side | Docs uploaded to server | Good (server resources) |
| BentoPDF | Client-side (WASM) | Docs never leave browser | Limited (~200 MB) |
| Gotenberg | Server-side | Docs uploaded to server | Good (server resources) |
| SignaturePDF | Server-side | Docs uploaded to server | Good (lightweight) |
Key trade-off: server-side tools (Stirling-PDF, Gotenberg, SignaturePDF) handle large files and complex operations but require document upload. BentoPDF keeps documents local but is constrained by browser resources and cannot run OCR or Office conversion.
Deployment Comparison
| Tool | Docker | ARM64 | Bare Metal | Stateless |
|---|---|---|---|---|
| Stirling-PDF | Yes (3 variants) | Yes | No | Yes |
| BentoPDF | Yes | Yes | Yes (static) | Yes |
| Gotenberg | Yes (only) | Yes | No | Yes |
| SignaturePDF | Yes | Community | Yes (PHP) | Yes |
All four tools are stateless – they do not store documents permanently. This simplifies deployment, scaling, and backup.
Licensing Comparison
| Tool | License | Free Tier | Paid Tier |
|---|---|---|---|
| Stirling-PDF | MIT (core) | Full UI + API; no OIDC | Pro: $99/mo or $1K/yr; OIDC |
| BentoPDF | AGPL-3.0 | Full features | $49 lifetime commercial license |
| Gotenberg | MIT | Full features | None (fully free) |
| SignaturePDF | AGPL-3.0 | Full features | None (fully free) |
Most permissive: Gotenberg and Stirling-PDF (MIT) – no copyleft obligations.
AGPL consideration: BentoPDF and SignaturePDF use AGPL-3.0, which requires source disclosure if the software is offered as a network service. This may complicate customer deployments where customers modify the tool.
Tools
5 tools.
BentoPDF
BentoPDF is a privacy-first PDF processing tool that runs entirely in the browser using WebAssembly. Unlike server-side tools like Stirling-PDF, BentoPDF processes all documents on the client – files never leave the user’s device.
License: AGPL-3.0-only (OSS) · Kind: web · Deploy: native, docker · SSO: none
ComPDF
ComPDF is a self-hosted, open-source PDF processing and conversion platform with a web dashboard and REST API, offering merge, split, OCR, encryption, and PDF/Office/image conversion via Docker Compose.
License: MIT (OSS) · Kind: web · Deploy: docker · SSO: none
Gotenberg
Gotenberg is a stateless, API-only PDF conversion engine. It has no web UI – all operations are performed via REST API calls.
License: MIT (OSS) · Kind: web · Deploy: native, docker · SSO: none
SignaturePDF
SignaturePDF is a lightweight, single-purpose PDF tool focused on adding signatures to PDF documents. It provides a simple web interface where users open a PDF, draw or place a signature, and download the signed result.
License: AGPL-3.0-only (OSS) · Kind: web · Deploy: native, docker · SSO: none
Stirling-PDF
Stirling-PDF is the most popular open-source PDF processing tool, with over 50,000 GitHub stars and rapid development.
License: MIT (OSS) · Kind: web · Deploy: native, docker · SSO: OIDC
