Prefix App vs Unit Converter Engineering Pro
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
Prefix App
Easily add a prefix to phone numbers before dialing without altering your contacts. Ideal for managing business phone lines or specific calling requirements directly from your address book or keypad.
- Full address book access
- Customizable contacts
- Recent calls list
- Customizable prefix and suffix
- Direct dialing via keypad
- Intuitive interface
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Prefix App is the App that let you put a prefix before the phone number without editing your address book. Very useful if you have a business phone. Features: - Full address book - Customizable address book - Recent calls - Customizable prefix; - Customizable suffix; - Direct call with phone keypad; - Simple, intuitive and smart interface;
Unit Converter Engineering Pro
This app provides precise unit conversions for engineers, scientists, and students. It supports over 100 units across 35 categories, including scientific notation and 9-digit decimal precision. The tool works offline and adheres to SI, NIST, and ISO standards.
- Over 100 units in 35+ categories
- Scientific notation support
- 9-digit decimal precision
- SI, NIST, ISO compliant
- Offline functionality
- Specialized units included
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Unit Converter Engineering Pro – The ultimate tool for engineers, scientists, and students who need precise and fast unit conversions. Easily convert between over 100 units across more than 35 categories commonly used in engineering, physics, chemistry, and mathematics. Perfect for professionals, researchers, and students who want a reliable, professional-grade converter at their fingertips. Included categories: • Acceleration • Angle • Area • Specific Heat • Electric Charge • Heat Transfer Coefficient • Length • Concentration • Thermal Conductivity • Physical Constants • Density • Diffusivity • Energy • Heat Flux • Force • Illuminance • Luminance • Mass • Moment / Torque • Power • ppm / ppb / ppt / % • SI Prefix • Pressure • Radiation – Activity • Radiation – Dose • Radiation – Exposure • Radiation – Equivalent Dose • Time • Volume • Velocity / Speed • Viscosity • Volume Flow Rate • Voltage / Electric Potential • Frequency • Temperature Key Features: • Supports scientific notation for extreme precision • Fully compliant with SI, NIST, and ISO standards • 9-digit decimal precision for engineering-grade accuracy • Fast and intuitive interface • Works offline – no internet required • Includes rare and specialized units often missing from other converters • Made by engineers, for engineers Simplify your work, save time, and ensure accuracy with Unit Converter Engineering Pro - your professional unit conversion companion. EULA: https://www.apple.com/legal/internet-services/itunes/dev/stdeula/
Screenshots
Verdict
The clearest difference is in-app purchases: Prefix App at none against Unit Converter Engineering Pro's 2. Prefix App also leads on iOS requirement (7.0 vs 13.0). On price, update cadence, ads 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
Both are free to download. Unit Converter Engineering Pro sells 2 in-app purchases, starting at $5.99 per 7 days. Prefix App asks for nothing beyond the download.
Prefix App ships an update fortnightly, Unit Converter Engineering Pro weekly. The most recent releases landed on October 9, 2026 and October 2, 2026 respectively.
| Parameter | Prefix App | Unit Converter Engineering Pro |
|---|---|---|
| Price | Free | Free |
| Rating | — | 5.0 (1 ratings) — better |
| Positive reviews | 48.3% of reviews | — |
| Number of ratings | — | 1 — better |
| Update frequency | Fortnightly | Weekly — better |
| Ads | No | No |
| In-app purchases | No — better | Yes |
| Monetization | Free — better | Free with in-app purchases |
| Devices | iPhone, iPod | iPhone, iPad, iPod — better |
| Requires iOS | 7.0 — better | 13.0 |
| Further details — not scored | ||
| Size | 21 MB | 77 MB |
| Age rating | 4+ | 4+ |
| Developer | Alain Lima | Kaiguri Tech |
Customer experience
Prefix App
Unit Converter Engineering Pro
In-app purchases
Prefix App
No in-app purchases
Unit Converter Engineering Pro
- 3-Day Trial3 Days trial$5.997 Days
- Yearly Plan$19.991 Year
Questions
Is Prefix App free?
Is Unit Converter Engineering Pro free?
Do Prefix App or Unit Converter Engineering Pro have ads?
Which is updated more often, Prefix App or Unit Converter Engineering Pro?
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