The questions we hear most

The beta is free until 31 January 2027. For companies, licences and terms are agreed on request.

Download the beta →

Yes. When the beta ends only the compression of new data closes: opening, extracting and verifying archives remains possible forever, even offline and even if our server were no longer running. Every future version of the program reads the archives written today.

Because the programs are not yet signed with Apple and Microsoft certificates. On macOS open it from System Settings, Privacy & Security, “Open Anyway”; on Windows from “More info” and then “Run anyway”. The SHA-256 fingerprint on the download page tells you whether the package is the right one.

How to install →

Every file is rebuilt and compared byte for byte before it is written, and the program was cut off abruptly 2,752 times while writing without losing an archive. It is still a beta: always keep the originals, and do not use it as the only copy of important data.

On office documents TSR goes down to 47.888% against 52.47% for 7-Zip at maximum; on JPEG photos it gains 18.2% where zip and 7-Zip gain nothing. On folders with tens of thousands of small files 7-Zip in solid mode leads by 2–7 points. TSR’s balanced profile always makes an archive smaller than zip -9.

All the numbers →

TSR creates and opens .tsr archives. You can put any file inside, zip, rar and 7z included: it compresses zips and Office documents better by taking them apart, the others go in as they are. To extract a .rar or a .7z, use the program it was made with.

You decide: choose one of the five levels, from Fastest to Slowest, or a time in seconds, and before starting TSR tells you duration, space and extraction time. For an order of magnitude: a hundred megabytes of text take 3 seconds at the balanced profile and 19 at maximum, on an Apple M5 Pro.

Time as the unit →

No. If there is one, TSR can use it for part of the work, and the archive stays identical byte for byte; on the balanced profile it is 1.4 to 2.9 times faster.

TSR is proprietary software, written from scratch. The open-source libraries it uses all have permissive licences, and they are listed with their licences inside every package.

To check for updates the beta sends only its version and the operating system. Crash reports and usage metrics leave only if you turn them on, and never contain file names, paths or contents; they stay ninety days on a server in the European Union, and you delete them yourself whenever you like. The files you compress never leave your computer.

The diagnostics privacy notice →

With a password the whole archive is encrypted with XChaCha20-Poly1305, file names included, and the key comes from the password through Argon2id: public, well-tested primitives, no home-made cryptography. Without the password the data cannot be recovered, so keep it safe.

Security and privacy →

Write to matteo@feroldi.cloud. For a vulnerability use the subject [TSR security] and do not publish details before the agreed date: the acknowledgement arrives within three working days.

The security policy →

Yes: the command line has JSON output and nine exit codes, and for servers there are a streaming service, a daemon with a job queue, a C library, .deb and .rpm packages and container images.

TSR for business →

Matteo Luigi Feroldi, in Vimodrone, near Milan. TSR was born on 21 July 2026 and is written from scratch in Rust; every published number has the measurement that supports it beside it, and negative results are written down like positive ones.