Comparison

LineKeeper vs PLC Ninja

Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.

Head to head
About

LineKeeper

Features
Read full description

LineKeeper turns your iPhone into a pocket HMI for the controllers on your plant floor — Allen-Bradley Logix, Siemens S7, and anything that speaks Modbus TCP. Scan the network and the app finds every PLC around and tells you which ones are ready to talk. On Allen-Bradley it reads the controller's own tag list over EtherNet/IP — live values in seconds, nothing to configure: no PLC program changes, no gateway, no OPC server, no cloud account. Values go straight from the controller to your phone. WHAT YOU CAN DO • Zero-config tag browser on Logix — every tag of every PLC, live, with search, including program-scoped tags. • Find by action — don't know the address? Press the machine's real button, or nudge a setpoint on its own screen, in the rhythm the app dictates — and the app finds the tag that followed. Works on Modbus and S7 too, where there are no tag names at all. • Network scan — one sweep fingerprints EtherNet/IP, Modbus TCP, S7 and more. A PLC with closed access shows as "found, access closed" with the exact steps to open it, down to the TIA Portal clicks. • One dashboard per machine, on multiple pages — number, gauge, LED and trend tiles on swipeable named pages ("Filler", "Capper", "Conveyors"), even when one machine runs several PLCs. • Operator panel — large start/stop buttons, hold-to-run jog, latches, setpoints and status lamps, full-screen kiosk mode with the screen kept awake. • Alarms and status codes — alarm words mapped to operator texts, a red banner over every screen while an alarm is active, and a session journal of appeared/cleared. • Machine history — a parameter snapshot of the controller taken at the first connection, plus a change log of every dashboard and panel tag: date and value of each change, kept on the phone across sessions. • Guarded writes — every write is confirmed and validated against the tag type and limits; hold-to-run releases the moment the app loses focus. • Machine profiles — PLCs, register maps, pages, panel and alarm texts saved as one profile and shared as a file: enter the register map once, the next shift sees names. • Built-in demo line — two virtual PLCs with a working panel so you can learn the whole app with no hardware. LINEKEEPER PRO (IN-APP PURCHASE) Reading is free forever. A one-time Pro purchase unlocks, on real controllers: writing setpoints and driving the operator panel, plus machine history — the parameter snapshot and the per-tag change log. Everyone who bought Write Unlock owns Pro automatically. The demo line includes every Pro feature free. WHO IT'S FOR Controls engineers, integrators and maintenance techs who need a quick window into a controller during commissioning, troubleshooting, or a line-down call — without carrying a laptop. HOW IT CONNECTS Your phone must be on the same network as the controller (plant Wi-Fi that routes to the PLC, or a USB-C Ethernet adapter). There is no cloud relay: if you can ping the PLC, the app can connect. SUPPORTED CONTROLLERS • Allen-Bradley CompactLogix and ControlLogix (the tag-based Logix 5000 family) over EtherNet/IP. • Siemens S7-300 and S7-400 out of the box; S7-1200 and S7-1500 with PUT/GET enabled and non-optimized DBs — the app shows the exact TIA Portal steps. Absolute addressing: DB, M, I/Q. • Modbus TCP devices — Schneider, VFDs, energy meters, WAGO, Delta and other Modbus slaves, with per-connection unit ID and word-order settings. Micro800, SLC-500, PLC-5, LOGO! and S7-200 use different protocols and are not supported yet. SAFETY Writing a value can move real machinery. You remain responsible for safe operation and must follow all site safety procedures. Never rely on the app for an emergency stop or any safety function. See the full terms at linekeeper.net/terms.html.

About

PLC Ninja

Access live PLC data directly from your mobile device. Connect via Ethernet, Wi-Fi, or serial adapter to monitor inputs, outputs, timers, counters, and analog values in real-time while in the field.

Highlights
  • Real-time PLC data monitoring
  • Ethernet, Wi-Fi, and serial connection support
  • View inputs and outputs
  • Monitor timers and counters
  • Access analog values
Features
Read full description

PLC Ninja puts live PLC data on your phone. Connect over Ethernet, Wi-Fi, or a serial adapter, and see every input, output, timer, counter and analog value updating in real time — standing at the panel, not walking back to the office. PLC Ninja is an independent product and is not affiliated with, endorsed by, or sponsored by Rockwell Automation, Siemens AG, AutomationDirect, or Mitsubishi Electric. Allen-Bradley, ControlLogix, CompactLogix, GuardLogix, MicroLogix, SLC 500, RSLogix and Studio 5000 are trademarks of Rockwell Automation. SIMATIC, S7 and LOGO! are trademarks of Siemens AG. DirectLOGIC is a trademark of AutomationDirect. MELSEC and FX are trademarks of Mitsubishi Electric. All product names are used only to identify the equipment this app can connect to. Terms of Use (EULA): https://www.apple.com/legal/internet-services/itunes/dev/stdeula/ Privacy Policy: https://plcninja-support.github.io/support/privacy.html

Screenshots

LineKeeper4 screens
PLC Ninja4 screens

Verdict

The call

The clearest difference is update cadence: LineKeeper at every 4 days against PLC Ninja's every 3 weeks. LineKeeper also leads on device support (3 vs 1) and iOS requirement (15.0 vs 17.6). On price, ads and in-app purchases 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

CostPrice · In-app purchases · Ads · Monetization

Both are free to download. LineKeeper sells 1 one-off in-app purchase and PLC Ninja sells 6 in-app purchases, starting at $3.99 per month. Whichever you choose, the download price is not the number that matters.

UpkeepUpdate frequency

LineKeeper ships an update every 4 days, PLC Ninja every 3 weeks. The most recent releases landed on October 4, 2026 and October 5, 2026 respectively.

Scorecard3 real differences · 7 level
LineKeeper versus PLC Ninja: the parameters behind the verdict, then further details
ParameterLineKeeperPLC Ninja
PriceFreeFree
Rating—5.0 (3 ratings) — better
Positive reviews—100.0% of reviews
Number of ratings—3 — better
Update frequencyEvery 4 days — betterEvery 3 weeks
AdsNoNo
In-app purchasesYesYes
Monetization—Free with in-app purchases
DevicesiPhone, iPad, iPod — betteriPhone
Requires iOS15.0 — better17.6
Further details — not scored
Size19 MB10 MB
Age rating4+4+
DeveloperOleksandr MakarovSHAOHUA YI

In-app purchases

1 purchases

LineKeeper

One-time1
  • Write Unlock$59.99
6 purchases

PLC Ninja

Subscriptions6
  • Standard$3.991 Month
  • Professional$8.991 Month
  • Ultimate$14.991 Month
Show 3 more
  • Standard$39.991 Year
  • Professional$89.991 Year
  • Ultimate$149.991 Year

Questions

Is LineKeeper free?
LineKeeper is free to download, with in-app purchases available.
Is PLC Ninja free?
PLC Ninja is free to download, with in-app purchases available.
Do LineKeeper or PLC Ninja have ads?
Neither LineKeeper nor PLC Ninja shows ads.
Which is updated more often, LineKeeper or PLC Ninja?
LineKeeper ships an update every 4 days, and PLC Ninja every 3 weeks. Most recently, LineKeeper was updated on October 4, 2026 and PLC Ninja on October 5, 2026.

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