What is Stirling PDF used for?

Stirling PDF is an open-core PDF platform with 50+ tools for editing, merging, signing, redacting and converting documents on desktop, in the browser or on your own server. It is a good fit for redacting and signing sensitive PDFs privately, automating bulk PDF processing, and offering an internal PDF service via API.

Is Stirling PDF open source?

Yes. Stirling PDF is open source under a custom licence. Its source code is on GitHub at Stirling-Tools/Stirling-PDF and is written mainly in Java.

Is Stirling PDF free?

Yes. Stirling PDF is open source, so the software itself is free to use under the terms of its own licence. Paid plans are also available, starting at $99 per month.

Can I self-host Stirling PDF?

Yes. Stirling PDF can be self-hosted on your own server or infrastructure.

What is Stirling PDF an alternative to?

Stirling PDF is an open-source alternative to Adobe Acrobat, iLovePDF, Smallpdf and Foxit PDF Editor. Other open-source alternatives to Adobe Acrobat include BentoPDF, PDFsam and Sioyek.

Is Stirling PDF actively maintained?

Yes. The most recent commit to Stirling PDF was on 2 October 2026, and the latest release is v3.0.2, published on 1 October 2026. The project has 93k stars on GitHub.

Stirling PDF: open-source alternative to Adobe Acrobat

About Stirling PDF

Stirling PDF is an open-source PDF editing platform that can run as a desktop app, in the browser, or on servers you control through a private API. The project's pitch is that documents can be edited, signed, redacted, converted and automated without being sent to an external service. It is written in Java and distributed with Docker for self-hosting.

It bundles more than 50 PDF tools, including merge, split, sign, redact, convert, OCR and compress. No-code pipelines in the interface let you automate repeated processing, and REST APIs cover nearly all tools for integration into existing systems. The interface is available in over 40 languages. Enterprise options include SSO, auditing and flexible on-premise deployments.

A quick start with Docker serves the app on a local port, and the documentation covers desktop and Kubernetes installs. The repository describes the project as open-core, and GitHub lists its license as 'Other', so confirm which features fall under which terms. It suits individuals and organizations that handle sensitive PDFs and prefer a self-hosted alternative to online PDF tools.

Key features

50+ PDF tools: merge, split, sign, redact
OCR, conversion and compression
No-code automation pipelines in the UI
REST APIs for nearly all tools
Desktop, browser and self-hosted server modes
SSO and auditing for enterprise deployments
Interface in 40+ languages

Good fit for

→Redacting and signing sensitive PDFs privately
→Automating bulk PDF processing
→Offering an internal PDF service via API

Built with: Java; Docker
Tags: pdf; pdf-editor; self-hosted; ocr; docker; java; document-processing; open-core

Stirling PDF: questions and answers

What is Stirling PDF used for?: Stirling PDF is an open-core PDF platform with 50+ tools for editing, merging, signing, redacting and converting documents on desktop, in the browser or on your own server. It is a good fit for redacting and signing sensitive PDFs privately, automating bulk PDF processing, and offering an internal PDF service via API.
Is Stirling PDF open source?: Yes. Stirling PDF is open source under a custom licence. Its source code is on GitHub at Stirling-Tools/Stirling-PDF and is written mainly in Java.
Is Stirling PDF free?: Yes. Stirling PDF is open source, so the software itself is free to use under the terms of its own licence. Paid plans are also available, starting at $99 per month.
Can I self-host Stirling PDF?: Yes. Stirling PDF can be self-hosted on your own server or infrastructure.
What is Stirling PDF an alternative to?: Stirling PDF is an open-source alternative to Adobe Acrobat, iLovePDF, Smallpdf and Foxit PDF Editor. Other open-source alternatives to Adobe Acrobat include BentoPDF, PDFsam and Sioyek.
Is Stirling PDF actively maintained?: Yes. The most recent commit to Stirling PDF was on 2 October 2026, and the latest release is v3.0.2, published on 1 October 2026. The project has 93k stars on GitHub.