Your data outlives the app.
Every commercial poker solver locks solved trees inside a proprietary binary only their own software can read. ART/GTO took the opposite road. The .artgto export is built on two open standards — zstd and CBOR — wrapped in a documented container layout. Anyone, in any language, with no proprietary tooling, can read it.
Commercial solvers store output in undocumented proprietary binaries. Reverse-engineering usually violates the licence; migrating between solvers is impossible. If the company shuts down, the libraries you paid for go with them.
Two open standards. One documented container.
The export is built on zstd for compression and CBOR (RFC 8949) for binary data encoding, wrapped in a short container layout. The full spec fits on a page. zstd and CBOR are maintained by IETF working groups and Facebook — not by a poker company.
Six guarantees, one file format.
Your data outlives the app.
If ART/GTO ceases development tomorrow, every .artgto file you own stays fully readable. The underlying encodings are maintained by IETF and Facebook, not a poker vendor.
No vendor lock-in.
Switching viewers, building your own inspector, integrating solved data into other tools — none of it requires permission. The file format is the API.
Web-native.
Header at the front, index at the end. HTTP range requests fetch just the section needed at any moment — browser viewers don’t download multi-hundred-MB files to display one runout.