Lambert vs GTK
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
Lambert
This application transforms your iPhone into a specialized geological compass. It accurately measures the dip direction and angle of geological strata, displaying real-time orientation data. Measurements can be enhanced with text and plotted on a map for easy transfer to your computer.
- Geological compass functionality
- Measure dip direction and angle
- Real-time stereographic projection
- Wulff and Schmidt Net projection diagrams
- Add text to measurements
- Plot measurement localities on a map
- Transfer data to computer
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This app turns your iPhone into a geological compass, a tool for each geologist. It can be used to measure the direction of dip and the angle of dip of geological strata. The app shows the current device orientation in a realtime stereographic projection. The data can be previewed in projection diagrams (Wulff and Schmidt Net) and transferred to your computer. You can add text to the measurements and plot the measurement localities on a map.
GTK
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GTK-Field is a field logging app for geotechnical site investigation. It works alongside you on site: record, describe, photograph, and produce a finished report on the same device. MODULES Trial pit with layer log and profile column Core drilling Dynamic probing Infiltration test Plate load test, dynamic Plate load test, static Sieve analysis with grading curve Sampling with lab tracking Site walkover General survey TO STANDARD Soil description and symbols to EN ISO 14688-1/2, presentation to DIN 4023. Probing to EN ISO 22476-2, sampling to EN ISO 22475-1, infiltration to OENORM B 4422-2. Static plate load test to OENORM B 4417 or DIN 18134, assessment to RVS 08.03.01 and RVS 08.15.01. The standards profile can be switched between Austria and Germany for each project. IN THE FIELD The app works entirely offline. All data stays on the device. Coordinates and elevation come from GPS or are entered by hand, photos belong to the exploration point. Reports are generated as PDF and can be viewed and shared directly on the device. ORDER Exploration points and samples receive sequential identifiers, and sample numbers are unique within a project. A sample register lists every sample of a project, with or without lab results. A combined export summarises the whole project with continuous page numbers. FREE GTK-Field is completely free. No subscription, no unlocking, no ads. NOTE GTK-Field is developed privately and is not a service of a chartered engineering practice. Calculated and estimated values must be checked by the user; professional responsibility for logging and interpretation remains with the user.
Screenshots
Verdict
The clearest difference is update cadence: GTK at every 9 days against Lambert's every 5 months. On price, ads, 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
Both are free to download. Neither carries in-app purchases, so what you see is what you pay.
Lambert ships an update every 5 months, GTK every 9 days. The most recent releases landed on October 3, 2026 and October 14, 2026 respectively.
| Parameter | Lambert | GTK |
|---|---|---|
| Price | Free | Free |
| Rating | 5.0 (4 ratings) — better | — |
| Positive reviews | 75.0% of reviews | — |
| Number of ratings | 4 — better | — |
| Update frequency | Every 5 months | Every 9 days — better |
| Ads | No | No |
| In-app purchases | No | No |
| Monetization | Free | — |
| Devices | iPhone, iPad | iPhone, iPad, iPod — better |
| Requires iOS | 16.6 | 15.0 — better |
| Further details — not scored | ||
| Size | 3 MB | 7 MB |
| Age rating | 4+ | 4+ |
| Developer | Peter Appel | Matthias Kroell |
In-app purchases
Lambert
No in-app purchases
GTK
No in-app purchases
