PJFFfree vs Quel
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
PJFFfree
This app serves as a manual for piping parts, focusing on Japanese specifications. It lists commonly used items based on manufacturer data and public dimension tables, with all measurements in millimeters.
- Piping parts manual
- Japanese specifications
- Commonly used parts listing
- Manufacturer data integration
- Millimeter measurements
- JIS standards compliance
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It is a manual of piping parts. Only Japanese specification. We are listed at the discretion of the things that seems to be in common use based on manufacturer's data and the dimension tables of dealers that are open to the public. Length units are in millimeters unless otherwise specified in decimal notation JIS standards compliance
Quel
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Quel is your all-in-one engineering toolkit for instrumentation and controls. Designed for process engineers, control engineers, and instrumentation specialists, Quel brings powerful sizing and calculation tools into one streamlined app. Whether you're working on valves, orifice plates, or temperature sensors, Quel helps you size, calculate, and verify with speed and accuracy. KEY FEATURES • Control Valve Sizing – Quickly determine Cv, flow conditions, and check for subcritical or critical operation. • Valve Performance Calculator – Evaluate installed gain, rangeability, and operating point across the full stroke range. • Orifice Plate Sizing – Built-in ISO 5167 calculations for DP, Beta ratio, and flowrate in engineering units. • Temperature Sensors – RTD and thermocouple resistance and millivolt reference tables for common sensor types. • Unit Conversions – Instant conversions across pressure, temperature, flow, and volume to simplify day-to-day calculations. • Save & Export – Save calculation results to history, export as PDF or text for documentation and field reports. • Engineering References – Quick guides and formulas used in the field for sizing and troubleshooting. WHY QUEL? • Fast & Reliable – Save time in the field or office with ready-to-use sizing tools. • Accurate – Built around standard engineering methods (ISA, IEC, API, ISO, ASME). • Practical – Designed by engineers, for engineers, with workflows that match real projects. • Portable – A professional-grade toolkit in your pocket, whether you're commissioning, troubleshooting, or reviewing designs. With Quel, you work smarter and more confidently on process control projects, knowing your sizing and calculations are consistent with industry standards.
Screenshots
Verdict
The clearest difference is in-app purchases: PJFFfree at none against Quel's 3. Quel's advantage is ads (none vs shown) and update cadence (every 5 days vs every 5 weeks). On price, device support and iOS requirement 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
Both are free to download. Quel sells 3 in-app purchases, starting at $9.99 per month. PJFFfree asks for nothing beyond the download.
PJFFfree ships an update every 5 weeks, Quel every 5 days. The most recent releases landed on October 8, 2026 and October 11, 2026 respectively.
| Parameter | PJFFfree | Quel |
|---|---|---|
| Price | Free | Free |
| Rating | 5.0 (1 ratings) — better | — |
| Positive reviews | 100.0% of reviews | — |
| Number of ratings | 1 — better | — |
| Update frequency | Every 5 weeks | Every 5 days — better |
| Ads | Yes | No — better |
| In-app purchases | No — better | Yes |
| Monetization | Ad-supported | — |
| Devices | iPhone, iPad, iPod | iPhone, iPad, iPod |
| Requires iOS | 15.0 — better | 15.6 |
| Further details — not scored | ||
| Size | 7 MB | 7 MB |
| Age rating | 4+ | 4+ |
| Developer | sigeyosi kanenishi | Guillermo Alvarado |
In-app purchases
PJFFfree
No in-app purchases
Quel
- Quel Monthly Plan$9.991 Month
- Quel Yearly Plan$69.991 Year
- Full Access$4.99









