What fields does each log entry contain?

Every row carries a timestamp, a device id, the sensor name, the numeric value, the unit, and a status of OK or ALERT. That mirrors the typical shape of an IoT telemetry record so your parser sees realistic columns.

How are alert readings created?

For the share you set as the fault rate, the tool deliberately pushes the value below the minimum or above the maximum of the sensor's normal band and stamps the row ALERT. This lets you verify that thresholds, alarms, and anomaly detectors actually fire.

What is NDJSON and why use it?

NDJSON is newline-delimited JSON, one complete JSON object per line. Log shippers, message queues, and streaming consumers expect this format because they can read and process one record at a time without parsing a whole array.

How are timestamps spaced?

The newest entry is stamped at the current time and earlier entries step backward by the sampling interval you choose, written in ISO 8601 UTC. This produces an ordered log that looks like it was collected over a real window.

Does anything leave my browser?

No. All readings are generated locally with no network calls, so you can produce large synthetic logs privately and offline.

Fake Sensor Log Generator

This tool generates fake IoT sensor logs — rows of timestamped readings with device IDs, units, and status flags — so you can test data pipelines, log parsers, and alerting rules without wiring up real hardware. A configurable fraction of readings are deliberately pushed out of range and marked ALERT, giving you anomalies to detect.

How it works

Each sensor type has a realistic normal band, for example temperature 18 to 26 degrees C or CO2 400 to 1200 ppm. For each entry the tool decides whether it is a fault based on your fault-rate percentage:

A normal reading is drawn uniformly from inside the sensor’s band and stamped OK.
A fault reading is pushed below the minimum or above the maximum and stamped ALERT.
The entry gets a rotating device id, the sensor name, the value, the unit, and an ISO 8601 timestamp.

Entries are spaced by your chosen interval with the most recent reading last, then rendered as CSV with a header row or as NDJSON with one object per line.

Tips and notes

Set the fault rate to a few percent to mimic occasional glitches, or higher to stress-test alert handling.
CSV is easiest for spreadsheets and quick eyeballing; NDJSON is what most log-ingestion and streaming systems expect.
The device id cycles through eight simulated devices, so you can test per-device grouping and filtering.