Read UK ITSO public transport smartcards with a Flipper Zero.
Tap your bus pass or rail smartcard on the back of your Flipper and see the tickets, passes, entitlements, journeys and pay-as-you-go balance stored on it.
ITSO is the UK's national standard for interoperable public transport ticketing. If you've got an ENCTS or Freedom Pass, a season ticket on a bus or rail smartcard, or a local authority travel card, it's probably an ITSO card.
Flipso reads ITSO cards over the Flipper's NFC reader, then decodes it and shows you everything that was on it.
Not sure what an NLC, a carnet or passback is? The glossary explains the railway, ticketing, ITSO and NFC terms used across Flipso, its screens and its source code.
ITSO cards contain a surprising amount of data in 4 KB of chip storage, all laid out by the ITSO TS 1000 specification. Flipso decodes as much of it as it can:
- Tickets — journey, period and carnet products, with operator, validity and the stations they cover
- Pay as you go — balance, owning operator and purse, and the most recent transactions
- Cardholder — name, date of birth, concession and entitlements
- Journeys — recent taps and completed journeys, with origin, destination, and fare
- Paper tickets — ITSO's compact paper tickets, like Glasgow Subway paper NFC singles, returns and day tickets: rides left, price, when and at which station they were last used
- NFC tag tickets — ITSO cards on NTAG215/216 and MIFARE Ultralight EV1 tags (CMD9 and CMD10), read like a smartcard, with the chip's lock bits and, on an NTAG, how many uses it has left
- Programmable cards — ITSO's applet-based media (CMD11), read without authenticating: products, value records and journeys, with the details the card keeps back until a reader proves itself said to be hidden
Station and operator names are resolved on the device from bundled reference data.
- A Flipper Zero
- ufbt, to build it yourself
- A UK ITSO smartcard
Flipso works on both official Flipper Zero and Momentum firmwares.
Download flipso.fap from the
latest release and copy
it to apps/NFC/ on the Flipper's SD card, or build and deploy Flipso to your
Flipper Zero yourself by running ufbt launch.
Copy data/naptan.dat to apps_data/flipso/naptan.dat on the SD card if you
want Flipso to decode bus stop NaPTANs. There are over 300k bus stops in the
UK (21 MB), so this data set is shipped alongside the app rather than bundled
into it.
Contributions are welcome — particularly operator names and card branding and fixes for cards that do not read.
Whilst Flipso has been developed and tested against real cards, some media types and IPEs are rather uncommon and I haven't seen them in the wild.
Some of these have been implemented speculatively based on the ITSO specification. As such some of the more unusual products are untested against real media.
Flipso is tooled out for AI-first development with Claude Code. When making changes, please keep the skills and tooling up to date.
Claude's tooling includes flipctl - a little python util that encapsulates
most of the problem solving required to develop/debug on a physical Flipper
Zero device connected via USB. This drastically reduces fault-finding cycles
and helps keep token usage down.
Claude has been carefully housetrained to develop responsibly according to my guidance and desire for unit tests. A good starting point is to scan your card for Claude. If you're building a large new feature Claude will benefit from synthesizing cards so he can test them on the device without needing you around to tap them.
Please leave Claude and coding agent attributions in commit messages so that we can retain history of code that was written using an agent.
Each version is a GitHub release
with its .fap attached, published by pushing a vX.Y tag - see
CLAUDE.md for the steps.
Flipso is free software released under the GNU General Public License v3.0.
Railway NLC codes kindly provided by railwaycodes.org.uk. A small donation has been made to Swindon Food Collective in exchange for the use of this dataset.
Rail ticket types from the Rail Delivery Group's ticket types reference data, and what each restriction code allows from its Knowledgebase Ticket Restrictions data feed, both published on the Rail Data Marketplace, under licence for free redistribution.
Bus stop NaPTANs published by the Department for Transport under the Open Government Licence.
Field offsets are taken from ITSO TS 1000 version 2.1.5 (March 2025), published by ITSO Ltd under the Open Government Licence. Each part is available to download from the ITSO technical specification site. Flipso is written against:
| Part | Title | Contents |
|---|---|---|
| TS 1000-0 | Concept and Context | An overview of the scheme |
| TS 1000-1 | General Reference | Data types: dates, timestamps, values, locations |
| TS 1000-2 | Customer Media Format and Data Record Definitions | The shell, directory, product (IPE) and value record layouts |
| TS 1000-5 | Customer Media Data and Customer Media Architecture | The fields of each product type, and the journey log |
| TS 1000-7 | ITSO Security Subsystem | Cryptography Flipso can't do without an ISAM |
| TS 1000-10 | Customer Media Definitions | Where the data sits on each kind of card (CMD2, CMD4, CMD7, CMD9, CMD10, CMD11) |
See docs/PROTOCOL.md for further information on Flipso's implementation.
docs/GLOSSARY.md explains the acronyms and terms it uses.