Licences and attributions

Last updated: 2026-09-19

Why this page exists

CLEKARA runs in your browser, which means the code that does the work is delivered to your device. Some of that code is open source software whose licence requires that you are told about it. This page is that notice.

Ghostscript — AGPL v3

The PDF compression tool uses Ghostscript 9.56.0, compiled to WebAssembly, Copyright © 2022 Artifex Software, Inc. Ghostscript is distributed by Artifex under the GNU Affero General Public License, version 3. The full licence text is at gnu.org/licenses/agpl-3.0.html.

Because this code is delivered to your browser, we are distributing it, and the AGPL requires us to offer you the corresponding source. Written offer: for at least three years from the date above, we will give anyone who asks the complete corresponding source of the Ghostscript build served by this site — the Ghostscript 9.56.0 sources and the scripts and container definition used to compile it to WebAssembly — for no more than the cost of the transfer. Write to hello@clekara.com and we will send it to you.

So that you can check you received the source of exactly this binary, the file we serve at /engine/gs.wasm is 16,177,271 bytes and its SHA-256 is 4dceaac93a7586722d76c48cf8632fdac8407db4400bdb9772eebf61758d4161. It is an unmodified build of Ghostscript 9.56.0: we have not patched the Ghostscript source.

The build also includes third-party components covered by their own licences: the URW++ base-35 fonts (AGPL v3), jbig2dec (AGPL v3), libjpeg by the Independent JPEG Group, zlib, libpng, libtiff, OpenJPEG, FreeType and Little CMS. This software is based in part on the work of the Independent JPEG Group.

Ghostscript and Artifex are trademarks of Artifex Software, Inc. CLEKARA is not affiliated with, endorsed by or sponsored by Artifex Software, Inc.

PDF.js — Apache License 2.0

Page rendering, document analysis and result validation use PDF.js 6.3.289, Copyright © 2024 Mozilla Foundation, licensed under the Apache License, Version 2.0. A copy of the licence is available at apache.org/licenses/LICENSE-2.0. The library is distributed unmodified.

pdf-lib — MIT

Merging, splitting, organizing pages and building PDFs from images use pdf-lib 1.17.1, licensed under the MIT licence. The library is distributed unmodified.

JSZip — MIT

ZIP downloads use JSZip 3.10.1. JSZip is offered under a choice of the MIT licence or GPL v3; CLEKARA uses it under the MIT licence. It bundles pako, also MIT.

Emscripten

The WebAssembly build of Ghostscript includes runtime code generated by Emscripten, licensed under the MIT and University of Illinois/NCSA Open Source licences.

Questions

If you need any of these licence texts, or the corresponding source of a component, write to hello@clekara.com and we will send it to you.