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.
zstd and CBOR, in a 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.
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.