Open source licences

This site runs on the open source software below. Full licence texts are on each project page.

Name Version Licence Used for
Flask 3.1.3 BSD-3-Clause Web framework
Werkzeug 3.1.8 BSD-3-Clause HTTP handling
Jinja2 3.1.6 BSD-3-Clause Page templates
MarkupSafe 3.0.3 BSD-3-Clause HTML escaping
itsdangerous 2.2.0 BSD-3-Clause Cookie signing
click 8.4.2 BSD-3-Clause Command line tooling
blinker 1.9.0 MIT Internal events
waitress 3.0.2 ZPL-2.1 Web server
cryptography 49.0.0 Apache-2.0 OR BSD-3-Clause Cryptography and signing
pyOpenSSL 26.3.0 Apache-2.0 TLS certificate handling
pycryptodome 3.23.0 BSD-2-Clause AND Unlicense Additional cipher algorithms
PyOTP 2.10.0 MIT Two-factor codes
webauthn 3.0.0 BSD-3-Clause Passkey sign-in
cbor2 6.1.3 MIT Passkey data decoding
Markdown 3.10.2 BSD-3-Clause Rich text rendering
Pygments 2.20.0 BSD-2-Clause Code highlighting
pillow 12.3.0 MIT-CMU Image processing
segno 1.6.6 BSD-3-Clause QR code generation
requests 2.34.2 Apache-2.0 Outbound price lookups
urllib3 2.7.0 MIT HTTP connections
certifi 2026.6.17 MPL-2.0 Trusted certificate list
idna 3.18 BSD-3-Clause Internationalised domains
charset-normalizer 3.4.9 MIT Character encoding detection
pyasn1 0.6.4 BSD-2-Clause Certificate structure parsing
cffi 2.1.0 MIT Native bindings

Software used only for development and testing, and not shipped, is not listed. Tell us if something is missing.