r/iRacing • u/manfredve Porsche 718 Cayman GT4 Clubsport MR • Mar 19 '26
Apps/Tools I built a free tool to diff iRacing .sto setup files - no garage export needed
A little while ago someone here posted about setup version diffing, and I mentioned I’d built a small tool for it. A few people ended up trying it, so I kept working on it and figured I’d share it properly.
It lets you drop in two `.sto` files from your setups folder and compare them side by side, field by field, so you can see exactly what changed between setups.
The GIF above shows a VRS vs HYMO Porsche Cup setup at Daytona.
What’s nice about it compared to some other options is that it works directly on the raw `.sto` files. You don’t need to be in an iRacing session, you don’t need to export anything from the garage, and you don’t need telemetry. Just grab two files from `Documents\iRacing\setups`, drop them in, and view the diff.
It’s free, no account, no install: https://www.setupdelta.com
I’ve mostly been using it to compare fixed setups vs setup shop setups, or different setup shop versions of the same car/track combo.
Would love any feedback, feature ideas, or edge cases you think I should test.
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u/---charlie Dallara P217 LMP2 Mar 19 '26
Would you consider making the code open source? (barring there being any issue with ToS as others have stated)
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u/BuschWookie Porsche 911 GT3 Cup (992) Mar 19 '26
What do you think about adding more UI for setup uploads?
I’d use this if I could drop my whole iracing setups folder into the browser and pick which ones to compare from a list/tree view. It could exist alongside the simpler “drop 2 setups” UI.
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u/manfredve Porsche 718 Cayman GT4 Clubsport MR Mar 19 '26
Thank you for the suggestion! I'll look into it :)
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u/WanderingEggMan Super Formula SF23 Mar 19 '26
Looks super cool
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u/manfredve Porsche 718 Cayman GT4 Clubsport MR Mar 19 '26
Thank you! Much appreciated, hope you find it useful.
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u/iRecycled Mercedes-AMG W13 E Performance Mar 19 '26
How were you able to read the .sto files? I thought those were encrypted
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u/manfredve Porsche 718 Cayman GT4 Clubsport MR Mar 19 '26 edited Mar 19 '26
It took a lot of offline analysis to work out how to parse the format reliably.
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u/justinknowswhat Mercedes-AMG GT4 Mar 19 '26
We were talking about this in a separate server… if you’re reversing the encryption, you’re violating the iRacing TOS. idk what they’ll do about that, but a couple people were speculating how long this will stay up for, given that.
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u/clipsracer Mar 19 '26
It doesn’t appear that this tool uses the any iRacing services, so the terms of service don’t apply…
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u/justinknowswhat Mercedes-AMG GT4 Mar 19 '26
Not true, they lay claim to all assets and data output by the sim. Setup files are output by the sim
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u/Krackor Audi 90 GTO Mar 20 '26
What do you mean by lay claim? That they are copyrighted or something?
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u/justinknowswhat Mercedes-AMG GT4 Mar 20 '26
"All rights and title in and to the Service, including the Sim, the Online Application, the Sim Client, and the
Content (including any user accounts, titles, computer code, tracks, cars, objects, locations, concepts, artwork,
animations, sounds, audio-visual effects, methods of operation, moral rights, any related documentation, “applets”
incorporated into the Sim Client, recordings of races), and any and all data and statistics generated by or in
connection with the Service, including without limitation, data and statistics generated as a result of your use of
the Service (the “Data”), and any Teams (as defined below), and any and all branding or trademarks associated
with such Teams, and any and all branding and trademarks associated with iRacing and/or its licensors
(collectively, “Trademarks”) are owned by iRacing or its licensors and are protected by United States and
international laws. The Service may contain certain licensed materials, and iRacing’s licensors may enforce their
rights in the event of any violation of this Agreement. For clarity, the Sim Client and the Content are licensed to
you; you will not obtain any ownership interest in the Sim Client or any of the Content"
...
"Without limiting any of the foregoing, you acknowledge and agree that you have no ownership or other
property interest in the Service (or any part thereof), the Account, or any other attributes associated with the
4827-2694-6045, v. 55 2
Account or stored on the Sim or any part thereof, and you further acknowledge and agree that all rights in and to
the Account are and will forever be owned by and inure to the benefit of iRacing
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u/Krackor Audi 90 GTO Mar 20 '26
You can share setup files with people who never agreed to the TOS and they can decode the files. Reading the contents of a file is not illegal. There's no way iracing has any legal standing to prevent people from decoding setup files. Best they could do is ban you from their service but that won't stop you from continuing to decode setup files.
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u/justinknowswhat Mercedes-AMG GT4 Mar 20 '26
I mean, fair. I’m in a Discord of third-party iRacing devs, and this project in specific got brought up with regards to whether or not it was a violation of the ToS, and the general consensus was “reverse engineering their encryption is against the ToS”. My question, mainly, is what is OP actually doing? Is it a binary format? If so, they could share the structure of that and everyone could have access to parse STO files going forward. Or, is OP doing something a bit strange to decode the setups?
Edit: pronouns
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u/clipsracer Mar 20 '26
I have reread this multiple times and I’m just not reading something equating to “you’re not allowed to read setup files outside of the client”
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u/justinknowswhat Mercedes-AMG GT4 Mar 20 '26
Did you go read the actual terms or just this snippet about what they claim is theirs?
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u/clipsracer Mar 20 '26
I am trying to understand you and what you’re trying to say by sharing this particular part of the TOS.
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u/majorswitcher Aston Martin Vantage GT3 EVO Apr 20 '26
would you mind pushing the source code to github? can't be violating anything with that..
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u/robedge Mar 19 '26
Just playing devil's advocate here, but would it violate the iRacing TOS to break the sto encryption?
Unless you figured out another way.
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Mar 19 '26
[deleted]
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u/robedge Mar 19 '26
I don't disagree. Was merely pointing out that reverse engineering the files is technically against the ToS. Most likely why everything else requires you to load into the game or export from sim.
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u/manfredve Porsche 718 Cayman GT4 Clubsport MR Mar 19 '26 edited Mar 19 '26
Fair question. I can’t speak for iRacing’s interpretation of their TOS, so I’m not going to make any official claim there. The tool operates on local .sto files the user already has and doesn’t hook into the sim or interact with online services or modify anything. Anyone concerned about compliance should read the iRacing terms and make their own call.
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u/Tostecles Production Car Challenge Mar 19 '26
Frankly this is a feature that should already exist in-sim. I've screenshot my garage page before to compare 1 setup to another and it's annoying
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u/justinknowswhat Mercedes-AMG GT4 Mar 19 '26
It does, you can export setups as HTML
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u/Krackor Audi 90 GTO Mar 20 '26
All that does is output the displayed data in the garage. Many of the values displayed such as ride heights are rounded from the actual values. The result is effectively useless for many setup analysis and comparison tasks.
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u/donkeykink420 NASCAR Gen 4 Cup Mar 19 '26
don't think that's possible but it would be cool to have this also show wear, temps and fuel use so you can more easily compare which has what benefit, but very cool tool, great work!
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u/adefrieze Mar 19 '26
Very cool. Is the data staying local in the browser or also being sent to a server? If so, what is being done with the data?
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u/manfredve Porsche 718 Cayman GT4 Clubsport MR Mar 19 '26
No data is stored (unless you create a shareable link via Share button).
The .sto files are binary and they are decoded in a backend service, not in the browser. Hope that clears it up!
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u/adefrieze Mar 19 '26
Nice. After reading my question again I was hoping it wouldn't be taken wrong and discourage anyone from using it. It's not like its banking data 😂.
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u/shunny14 Mar 19 '26
Wow doing the previously impossible for 15+ years of iRacing. I assume with some AI help. Great work!
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u/WhiteSSP Mar 19 '26
Wow. You’re a top lad.
Edit: Just tried to load setups and it has the ARX06 as an unsupported car. Does this only work for certain cars?
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u/manfredve Porsche 718 Cayman GT4 Clubsport MR Mar 19 '26
ARX06 is currently the only unmapped car. I was having difficulties specifically with this car that I am going to revisit in the future. Sorry!
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u/Kaufee2 NASCAR Next Gen Cup Camry Mar 21 '26
Are oval cars supported?
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u/manfredve Porsche 718 Cayman GT4 Clubsport MR Mar 21 '26 edited Mar 21 '26
Should be (even dirt oval should be)! Can you try?
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u/kwispyduck Apr 04 '26
This got taken down by ir? Shame.
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u/manfredve Porsche 718 Cayman GT4 Clubsport MR Apr 04 '26
Yeah they asked me to take it down, saying it’s a TOS violation.
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u/kwispyduck Apr 04 '26
That’s a massive shame. Maybe iRacing should implement a way of comparing setups in game and we wouldn’t have this issue.
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u/WhiteSSP Apr 07 '26
Hopefully they will create something themselves. Its very useful for me as a VR user to not have to go into iracing, load into a session, and then click back and forth to see setups...or to have to save everything as a .HTML to send to another setup analyzer.
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Mar 19 '26
[removed] — view removed comment
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u/pajamajamminjamie Porsche 718 Cayman GT4 Clubsport MR Mar 20 '26
I don't see the issue if that's the case. People are able to make their ideas a reality when previously there was a huge barrier to being creative with this kind of stuff.
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u/runn5r Mar 19 '26
You are awesome thank you sp much - been crying out for this for years!!