Plugins — customize messages for flespi devices

Complement and/or transform your device data to meet the requirements of a third-party platform.

Plugins are used to inject, delete or modify data received by the flespi devices to prepare it for further consumption and use in a variety of cases such as streaming into government-regulated systems, toll roads services, various telematics data aggregators, and the like.

The device plugins can be used to:

  • Attach custom static information to devices and use it in REST selectors. For example, add your customer id or phone number field to devices. Note: this custom info will not be added to the device JSON messages.

  • Add and store custom information as a part of the device JSON message. As a result, this custom data will be available in device telemetry, via MQTT, in streams, and for analytics.

  • Validate data received from the device and retain validated parameters value. If the message doesn't pass validation expression, the plugin won't be applied to the message at all.

  • Delete specified parameters from the received messages.

  • Add custom parsing based on the user-defined parsing scheme written using our special PVM language.

Plugins for devices define the schema of fields, how to validate field values, and what to do with them at different stages of the flespi message pipeline process. The current configuration of devices attached to the plugin can be retrieved via the REST API or by subscribing to flespi/state/gw/plugins/+/devices/+ MQTT topic.

Types of plugins

Below is the list of currently supported plugin types:

Plugin type



add static fields to the designated item, some of the fields can be stored as message parameters


add cached telemetry values in place of missing device message parameters


add new message parameters as a result of evaluating expressions


remove the listed parameters from the message


execute PVM code to process the message


resolve the position address using Google reverse geocoding and add it to the message


resolve the position address using Nominatim reverse geocoding (OSM) and add it to the message. Public and private servers supported.


resolve the position address using Here reverse geocoding and add it to the message


resolve position address using reverse Gurtam Wialon geocoding and add it to the message


resolve position coordinates using LBS Wialon geocoding and add them to the message

Plugins priority

If you assign several plugins to a device, you may want to apply them in a specific order. Use the priority parameter in the plugin configuration to arrange the required order. The higher the number in the priority field, the earlier the plugin will apply.

Data validation

Use the validate_message field in the plugin configuration to specify the validation expression that should succeed for the plugin to apply. If no validation expression is specified, the plugin will apply to all messages.

flespi plugin configuration validate message


Use the timezone field in the plugin configuration to specify the correct timezone for all time/date-related operations in selectors and counters.

flespi plugin configuration timezone


Read a comprehensive article on plugins here.

See also
Using plugins to resolve position coordinates into address using Here reverse geocoding API and add it into the device messages.
Configuring custom parsing for NMEA-formatted GPS data to convert it into JSON message with standardized parameters.