Project overview

Your engine runs on a file. The computer that controls it keeps its whole program — and every tuning table — in one plain file, usually a few megabytes.

Most of the time that file is a mystery. A tuner hands you one back and you have no easy way to see what they changed.

OpenRemap opens it. Free, open source, and it runs on your own computer: no account, no telemetry, nothing uploaded.

What you can do with it

• Find out what a file is. Which manufacturer made the ECU, which family it belongs to, which software version it runs — in about a second, without an internet lookup.
• See if it is healthy. Checksums, tuning tables, empty regions, duplicated VINs — one command, one verdict.
• See what a tune changed. Byte by byte and table by table: which maps moved, and by how much.
• Keep the change. Save it as a recipe — a small, readable text file of "at this spot, these bytes become those bytes" — and apply it to another file of the same software, with a check at every step.
• Know what it doesn't know. Where a table has no name, you get its offset and the values that were measured — never a guess dressed up as a fact.

Why it's different

Most tuning workflows are a black box: you hand over a file, you get one back, and nobody shows you the middle. OpenRemap is the opposite.

• The answers come with evidence. Every identification carries the signals behind it and a confidence tier, so you can disagree with it.
• Nothing is hidden. The code that recognises an ECU family is open and readable, and the recipe it writes is plain JSON — not a proprietary blob.
• Your files stay yours. It works offline and never uploads a dump, not even when you contribute support for a new ECU family.

Who it is for

• You bought or inherited a tuned file and want to know what is in it before it goes anywhere near your car.
• You are learning about tuning and want to see the actual bytes, not a wizard's summary screen.
• You work with dumps all day and want an offline, scriptable tool that explains its answers.

No knowledge of tuning or programming is needed to start — the glossary defines every word as it comes up.

What it does not do

• It does not flash your car. OpenRemap writes files; it never talks to a vehicle.
• It does not correct checksums. It reports whether they are still valid (ok, fail, or skip when it knows no scheme for that family) and leaves the correction to your tuning tool.
• It does not create tunes. It records the changes a person made and replays them faithfully.
• It does not make a tune safe. A file that will be flashed into a real car needs a qualified tuner's review first.

Ways to use it

The TUI, CLI and API are available today; the Harness is the next milestone. All of them need Python 3.10 or newer, on Windows, macOS or Linux.

No dump to experiment with? openremap synth --output demo.bin writes a synthetic ECU-like file you can point any of them at.

Where the project stands

Version 0.9.0, MIT licensed: 38 extractors covering the ECU families of six manufacturers — from 1980s Bosch LH-Jetronic to modern Bosch EDC17 and the Denso / Hitachi units in Subarus. What changed recently: release notes.

Where to go next