Open source licenses
The site is built on open source software. This page lists every third-party component that loads in your browser — libraries, fonts and data files — with its license and a link to the source.
Libraries
React
MITUsed for the interface of the whole site
React DOM
MITUsed for the interface of the whole site
Next.js
MITUsed for page rendering and navigation
PDF-LIB
MITUsed for PDF tools, printable calendar
fontkit (PDF-LIB build)
MITUsed for fonts embedded in PDFs
PDF.js
Apache-2.0Used for page previews in PDF tools
JSZip
MIT OR GPL-3.0-or-laterUsed for ZIP archives: favicons, QR codes, exports
QR Code Generator
MITUsed for QR code generator
jsQR
Apache-2.0Used for checking that a QR code scans
SparkMD5
MIT OR WTFPLUsed for MD5 hashes
gpt-tokenizer
MITUsed for token counter: OpenAI models
Tokenizers.js
Apache-2.0Used for token counter: open models
libheif (libheif-js)
LGPL-3.0Used for HEIC to JPG — shipped as a separate unmodified file you can replace with your own build
Fonts
Onest
OFL-1.1Used for headings and interface
Lora
OFL-1.1Used for body text and italic notes
JetBrains Mono
OFL-1.1Used for numbers, codes and results
PT Sans
OFL-1.1Used for Cyrillic text in generated PDFs
Data
DeepSeek-R1 tokenizer vocabulary
MITUsed for token counter
Qwen3 tokenizer vocabulary
Apache-2.0Used for token counter
GigaChat 3.5 tokenizer vocabulary
MITUsed for token counter
What the site does with visitor data is described in the privacy policy.