Last 30 days
Last 30 days
Avg per download
338 reviews
Last 30 days
Last 30 days
Avg rev. per download
338 reviews
Performance Insights
Category rankings
Competition level
Low competitionUnder 100K on both downloads and revenue — the kind of niche a small team can still take.
Tracked since
First seen September 2021 · 28 releases since
Lineman's Reference - XFMR LAB is an iOS app ($19.99) by Digital Apprentice LLC in the education category, holding #7 in the paid education charts. It draws an estimated 1K downloads a month and holds a 4.6-star rating.
- A paid app priced at $19.99.
- Ships new versions about one a month.
- Latest version is 2.0.6, released September 1, 2026.
- 79% of ratings are five-star.
- Available in 1 language.
- Strongest in US, CA, AU.
- Downloads at 64.7 MB and requires iOS 16.0+.
- Rated 4+.
App details
- Version
- 2.0.6
- Release status
- Worldwide
- Age rating
- 4+
- Requires
- iOS 16.0+
- Size
- 64.7 MB
- Languages
- English
- Price
- $19.99
- First seen
- September 2021
- Top markets
- US, CA, AU
- Publisher country
- US
- Website
- Visit website
- Support
- Visit support
Release history
28 versions tracked
- Version 2.0.6Latest
- Version 2.0.5
- Version 2.0.4
- Version 2.0.3
- Version 1.3.02
- Version 1.3.01
- Version 1.3.0
- Version 1.2.23
- Version 1.2.22
- Version 1.2.21
- Version 1.2.20
- Version 1.2.01
Ships about one a month.
What users say
- 5.0
Great training reference!
This is a great app, let me just start with that. It would be great if you could build your own banks and check voltage and what not. The set diagrams are awesome but being able to play around with different connections would make it better. Also tap changer settings and info would also be a great addition.
- 3.0
Love the app but…
Definitely some issues. I’ll wire up a bank correctly and it’ll tell me it’s wrong. I can delete my secondary’s and reconnect them exactly the same way and close the fuses again and it’ll say it’s right. Also, I’ll wire up a wye delta (for example) and it’ll say “this is a correct way to wire a delta delta bank” when obviously it should say wye delta. Lastly the app needs to be run with a horizontal screen but you can’t put the volt meter on the c phase secondary leads because of the layout. Still worth the $10 with the few issues it has
Reviewed on version 1.0.16
- 4.0
Great app, let’s take it up a notch
How about being able to select transformers from a list (a.k.a. transformer dock)so to be able to bank subtractive and additives transformers. Also, would like to be able to tie three phase secondary legs on the open secondary lines below transformers instead of tying secondary bushings then dropping one leg to secondary. Just suggestion to make people understand the beast. UPDATE! The developer has contacted me that they are already moving towards these improvements!!
Reviewed on version 1.0.14
About Lineman's Reference - XFMR LAB
3,227 characters
Learn it. Wire it. Energize it. Check your work.
Built by a working journeyman lineman for linemen and their apprentices. The XFMR Lab simulates distribution transformer banks driven by your own wiring — the metering, fusing, and faulting all behave the way you'd expect in the field.
NEW IN 2.0 — BUILT-IN TRANSFORMER TRAINING (Replacing XFMR INFO)
Six guided lessons take you from "what's a transformer?" to wiring a 3-pot bank: • Start Here — What is a Transformer? • Dual H Bushings — The Two Wirings & the Nameplate • The Tap Changer — One Pot, Multiple System Voltages • Three-Phase — The Three Phases and How They're Related • Bank Identification — Delta or Wye, Open or Closed • Your First Bank: Delta-Wye Closed (120/208) • More lessons on the way!
Work the lessons in order, or jump straight to the labs.
ALSO NEW IN 2.0
• The Sandbox (Beta) — wire anything from scratch in a COMPLETELY-customizable lab, with live, vector-based voltage and fault logic baked in. • Death Traps — scenario-based transformer traps linemen run into — and how to navigate them safely. • A brand-new look across every lab — new graphics, sharper, faster, & easier to read in the field. • Voltmeter you can now drag with two fingers; readings update as the leads move. • Parallel the secondary coils by hand in wye secondary labs • Stats that track lab completions, quiz scoring and for-fun stuff like the number of fuses you've blown. • User Customizations - the user can now alter the spec of their labs; from grounding to parallel coil cutover-direction, requiring the 4th cutout, tap changer implementation and more. • 2.0 is FREE for everyone who already owns XFMR Lab — thank you for years of feedback and encouragement.
WHAT YOU GET
Single Phase — Single Bushing · Dual Bushing Three Phase (closed) — Delta-Delta · Delta-Wye · Wye-Delta · Wye-Wye Three Phase (open) — Open Delta-Delta · Open Wye-Delta Misc — Paralleling · 4th Cutout · Death Traps (6 Scenarios) Advanced — Straight 480 · 240/480 · 277/480 · Corner-Grounded 240/480 · Wye-Wye 5-Wire (120/240 + 120/208) - all now able to be wired up Wye AND Delta on the topside The Sandbox (Beta) EVERY FUTURE UPDATE IS FREE - THE APP IS A ONE-TIME PURCHASE. I'm always working on new updates.
TOOLS & REFERENCE
• Volt, ohm and rotation meters with real behavior • Nameplate, secondary coil and tap changer animations • Reference diagrams for every standard bank
Learning Mode walks apprentices through every wrong-connection check. Journeymen and experienced users can keep this turned off if they'd like.
QUIZZES
• Classic Quiz — Select each lab you want in your quiz - with graded scoring across each lab. • Advanced Quiz — You're provided with the job-site info and need to pick the right nameplate and coil setup, then wire it. • Bank ID - A beginner's quiz tied into the new XFMR Training lesson plan. The user is provided with different primary and secondary wirings and must correctly identify them.
Used by 30,000+ linemen since 2021.
Questions? Suggestions? Reach me at [email protected]
Screenshots
8 iPhone screenshots
Lineman's Reference - XFMR LAB iOS app generates an estimated monthly revenue of $20K.
Lineman's Reference - XFMR LAB iOS app download estimates are updated daily. The app maintains a 4.6-star rating based on 338 user reviews, indicating strong user satisfaction in the mobile app market.
Lineman's Reference - XFMR LAB iOS app competes actively in the mobile app category. The app's performance metrics suggest significant growth potential in a low-competition segment.
You can download Lineman's Reference - XFMR LAB iOS app from the App Store for iOS devices, requiring iOS 16.0 or later. The app provides its core features without requiring in-app purchases.
View on App Store