Which fits your needs?
NullDisk: Mac users managing local/remote storage, and developers who need Git-aware cleanup or scriptable disk reports.
WhatSize: Mac users who favor column browsing and integrated duplicate/cleanup tools.
Features, pricing, and workflow
Scroll across to compare
| Feature | NullDisk | WhatSize |
|---|---|---|
| Best fit | Mac users managing local/remote storage, and developers who need Git-aware cleanup or scriptable disk reports. | Mac users who favor column browsing and integrated duplicate/cleanup tools. |
| Visualization | Radial map, treemap, and file list; CLI terminal treemap | Size-sorted columns and measurement views |
| Platforms and requirements | Mac app: macOS 14+; CLI: macOS, Linux, Windows | macOS 11+ (current vendor requirements) |
| Pricing and editions | Direct Mac edition free with reminders; optional $9.99 one-time personal license or team seat removes reminders. App Store terms are separate. | Vendor lists $14.99 and a 30-day trial; upgrades may be priced separately. |
| Open source | No | No |
| Native macOS UI | Yes | Yes |
| Cleanup workflow | Review source and action: local Trash, explicit permanent removal, or backup/delete; remote and cloud actions depend on the destination. | Review the chosen cleaning or duplicate action before applying it. |
| Reports and portability | CLI produces JSON/NDJSON scan reports. Third-party scan files are not directly imported into the Mac GUI. | Preserve any saved measurements or reports supported by your version. The cited overview does not establish an import format shared with NullDisk. |
NullDisk: what stands out
A good fit for Mac users managing local/remote storage, and developers who need Git-aware cleanup or scriptable disk reports.
NullDisk: strengths
- Radial and treemap views with local, SSH, and cloud sources
- Git-aware development cleanup for generated output and eligible worktrees
- Native Mac UI plus terminal UI and JSON/NDJSON CLI reports
Considerations
- Desktop GUI requires macOS 14+; Linux/Windows use the separate CLI
- Mac app sends anonymous usage telemetry; no in-app opt-out at this review
- No content-based duplicate finder; allocated bytes are not a guaranteed recovery total
WhatSize: what stands out
A good fit for Mac users who favor column browsing and integrated duplicate/cleanup tools.
WhatSize: strengths
- Size-sorted columns and detailed filtering
- Duplicate-file tools and cleanup categories
- Updates measurements as the filesystem changes
Considerations
- Paid license after the trial
- Cleanup categories still require your judgment
- Check upgrade terms separately from the initial purchase
For a useful comparison on your own drive, match the scan root, access permissions, and size mode. Chart style changes how you explore the results; it does not by itself establish measurement accuracy.
Common questions
When should I choose NullDisk?
A good fit for Mac users managing local/remote storage, and developers who need Git-aware cleanup or scriptable disk reports. Direct Mac edition free with reminders; optional $9.99 one-time personal license or team seat removes reminders. App Store terms are separate.
When should I choose WhatSize?
A good fit for Mac users who favor column browsing and integrated duplicate/cleanup tools. Vendor lists $14.99 and a 30-day trial; upgrades may be priced separately.
Will both apps show the same size?
Not necessarily. Match the scan root, permissions, exclusions, and logical/allocated-size mode. Hard links, APFS clones, snapshots, sparse files, and cloud placeholders can change totals. A reported size is not a guaranteed amount recovered after deletion.