Pydantic AIPython agent framework from the Pydantic team for building type-safe GenAI apps.

What is a span?

A span is the building block of a trace, represented by a single row in the Logfire live view. Spans have start and end times, attributes (key-value metadata), and can nest under parent spans. Multiple (nested) spans form a trace, which represents a complete request flow or operation.

Asked by Sami Virtanen · Mar 29, 2026

What is a log?

A log is the record of an event. A flat data structure with timestamp, level (debug, info, warning, error, critical), and a message. Although Logfire can receive logs, we recommend you use it to store high-value events from your application, such as spans and traces.

Asked by Damian Wysocki · Mar 30, 2026

What is a metric?

A metric is a collection of datapoints at intervals. When stored with timestamps, metrics become timeseries. While traces show what happened in a request and logs capture single events, metrics show trends across your system.

Asked by Xavier Costa · Mar 3, 2026

What is a guest?

A guest is a read-only user that can be invited directly to a Logfire project, but not to an organization. Guests are similar to outside collaborators in GitHub.

Asked by Beatriz Costa · Feb 25, 2026

What happens if I use more than the free allowance?

For all plans we'll send you emails and in-app alerts on your level of use. On Personal, if you go well over the free allowance, we'll eventually stop ingesting new data, and you might see warnings in stdout/stderr about 4XX responses from the Logfire API. For Team, Growth and Enterprise customers you'll be charged at the plan specific rate for your additional usage.

Asked by Malik Rasheed · Feb 12, 2026