The cache that does not come back
A MIT Mac disk explainer that deletes rebuildable caches and trashes your own files.
- Category
- Developer tools
- Who it is for
- A developer on macOS 15 whose disk filled up with tool caches.
- Possible model
- Open source
- Difficulty
- Medium
- Inspired by
- whyfull · whyfull
- Original launch
- Watch the launch · Oct 24, 2026
Difficulty is an editorial estimate of technical and operational complexity, not a score.
Startup idea analysis by Startup Ideas. Last reviewed Oct 25, 2026. How we read a launch.
The startup idea
Behnam posted whyfull on October 24. A Mac used for code fills up with node_modules, Xcode simulators, Docker's disk, the npm cache, Ollama models, and agent caches. whyfull finds that, explains it, and clears it safely. The repository is behnamazimi/whyfull. The license is MIT. You need macOS 15 or later. It shows what is using the space and changes nothing until you review and confirm. Caches that apps rebuild are deleted. Your own files go to the Trash, where you can change your mind. A big folder it does not know is labeled "Not recognized." It never sends a report on its own. You paste one yourself if you want a new rule. The post says safely. It does not say a cache is deleted rather than trashed, or that the app starts at macOS 15. This page did not free any space.
The opportunity is the plain name on a folder a developer forgot. A smaller product is the plan, with two verbs: delete for caches, Trash for your files. A cleaner that treats both the same is not this readme.
Do not say every removal can be undone. Caches cannot. Do not say it uploads a scan.
The problem
The disk is full, and the biggest folder has a name you do not recognize.
Who would pay for this?
- Primary
- A developer on macOS 15 whose disk filled up with tool caches.
- Secondary
- Someone who will read a plan before pressing confirm.
- Early adopter
- One scan, no delete, then one cache group the person picks.
How could it make money?
Possible models. Nothing here is a claim about what whyfull charges.
- No price. MIT.
- Homebrew is the install.
- The post does not name a paid tier.
What would the MVP look like?
- A scan that names the big folders.
- A plan you confirm.
- Caches marked deleted, your files marked Trash.
- Not recognized left alone.
How to validate the idea
- Ask five people which pile went to the Trash and which was deleted.
- If they cannot say, the two verbs were hidden.
- Do not run it on a Mac older than 15 and call that supported.
How to differentiate
- It explains the folder before it offers to remove it.
- Nothing happens before confirm.
- It does not phone home.
- Do not become a general backup app.
Original product launch
This launch is inspiration and evidence that someone shipped, not a partnership. The idea above is our reading of the broader opportunity. whyfull did not write it.
- Product
- whyfull
- Source
- whyfull
- Film
- whyfull, caches do not go to the Trash
- Posted
- Oct 24, 2026 · 0:44
Product that inspired this idea
Behnam's post says a Mac disk fills up with node_modules, Xcode simulators, Docker, npm cache, Ollama models, and agent caches. whyfull finds them, explains them, and clears them safely. The readme says MIT. You need macOS 15 or later. It changes nothing until you review and confirm. Caches that apps rebuild are deleted. Your own files go to the Trash. A folder it does not know stays "Not recognized," and it never sends a report on its own. The post does not say caches are gone for good, or that the floor is macOS 15. This page did not delete a cache.
Posted by @baz7c8. Watch the original launch. No separate product site is listed unless the post itself is the source.
- macos
- disk
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