TC66C vs Diskio
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
TC66C
Connect to a Type-C tester via Bluetooth to view and control its data. This utility app allows for real-time monitoring and management of tester functions directly from your device.
- Bluetooth connectivity
- Type-C tester data display
- Tester control functions
- Real-time monitoring
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Data display and control of the tester by connecting the Type-C tester via Bluetooth
Diskio
This utility app provides precise speed tests for all your storage devices, from internal iPhone storage to external USB drives. Customize test parameters for detailed insights and identify performance bottlenecks. It offers a simple three-step process to analyze your storage's true capabilities.
- Precise disk speed testing
- Tests internal and external storage
- Customizable test parameters
- Simple three-step process
- Universally compatible with iOS devices
- Identifies performance bottlenecks
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How fast is your storage? Measure sequential read and write speeds on your iPhone or a compatible external drive. Go beyond one number with repeat runs and a detailed report. SEE THE WHOLE RESULT Choose 1, 3 or 6 runs. With 3 or 6 runs, see median read and write speeds, minimum and maximum values, and the result of every run. CHECK CONSISTENCY Choose 6 runs to assess read and write stability separately over the last five. See whether results are stable or vary, with the criteria explained in the app. TEST YOUR SETUP Use your iPhone's internal storage or select a compatible, writable external drive through Files. Choose a test file from 1 to 5 GiB and a block size of 1, 2, 4, 8 or 16 MiB. The defaults are 6 runs, a 1 GiB file and a 2 MiB block. UNDERSTAND THE MEASUREMENT Diskio 3.0 reworks the speed calculation and test-file sizing. Speeds are shown in MB/s, and write timing includes final filesystem synchronization. Follow each write and read phase as the test runs. SHARE THE DETAILS Send a result card with the full report, test settings and, after 6 runs, the stability assessment. The redesigned interface supports light and dark appearances, larger text and Reduce Motion. GET STARTED 1. Select your storage and test settings. 2. Start the test and keep Diskio open. 3. Review the report or share your results. A test needs enough free space for a temporary file. External storage must be accessible and writable through Files. Results depend on the device, storage, connection, free space and test settings. The stability assessment adapts numerical criteria from SNIA SSS PTS. It is not a full SNIA-compliant benchmark, a drive-health check or a sustained-performance rating. Measurements in version 3.0 may differ from earlier versions because the method has changed.
Screenshots
Verdict
The clearest difference is price: TC66C at Free against Diskio's $5.99. TC66C also leads on ads (none vs shown) and iOS requirement (9.0 vs 16.0). Diskio's advantage is rating (3.9 vs 2.0) and update cadence (weekly vs every 2 months). On ratings volume, in-app purchases and device support there is nothing between them.
Scored on Price · Rating · Positive reviews · Number of ratings · Update frequency · Ads · In-app purchases · Monetization · Best chart rank · Devices · Requires iOS
TC66C is free to download; Diskio costs $5.99 up front. Neither carries in-app purchases, so what you see is what you pay.
Diskio holds the better App Store score, 3.9 against 2.0. Both are backed by a comparable volume of ratings — 6 and 17 respectively. Written reviews point the same way: 33% of TC66C's written reviews are positive against 44% of Diskio's.
TC66C ships an update every 2 months, Diskio weekly. The most recent releases landed on June 29, 2026 and September 29, 2026 respectively.
| Parameter | TC66C | Diskio |
|---|---|---|
| Price | Free — better | $5.99 |
| Rating | 2.0 (6 ratings) | 3.9 (17 ratings) — better |
| Positive reviews | 33.3% of reviews | 44.4% of reviews — better |
| Number of ratings | 6 | 17 — better |
| Update frequency | Every 2 months | Weekly — better |
| Ads | No — better | Yes |
| In-app purchases | No | No |
| Monetization | Free — better | Paid |
| Devices | iPhone, iPod — better | iPhone |
| Requires iOS | 9.0 — better | 16.0 |
| Further details — not scored | ||
| Size | 37 MB | 10 MB |
| Age rating | 4+ | 4+ |
| Developer | 亮亮 刘 | Sergii Khliustin |
Customer experience
TC66C
Diskio
In-app purchases
TC66C
No in-app purchases
Diskio
No in-app purchases









