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LangWatch Cloud bills on ingested events per billing period. This page is the complete list of what produces one, so you can predict a bill from your own workload rather than from a sample.
Self-hosted deployments are not metered and send no usage data to LangWatch. This page applies to LangWatch Cloud. See Editions and licensing.

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The complete list

These are the only events that increment your count. Everything else the platform does is free. Spans dominate the count for most customers. A single trace of an agent turn typically contains several spans, one per step.

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Reading an experiment’s cost

An experiment is not one event. A run over 100 dataset rows with 2 evaluators produces roughly 1 started + 100 target results + 200 evaluator results, so around 301 events. This is worth knowing before a large sweep.

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Reading a simulation’s cost

A scenario run produces one started event plus one snapshot per conversation turn, so a 10-turn simulation is about 11 events.

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What is never billed

  • Reading your data: dashboards, the trace explorer, analytics queries, and search.
  • Anything you create: prompts, evaluators, scenarios, agents, datasets, dashboards, custom graphs, automations, projects, or teams.
  • Users. Seats are priced separately from events, not metered as events.
  • Retries and replays of an event you already sent (see deduplication below).
  • Platform-internal work: projections, rollups, queue processing, and background jobs.

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Deduplication

Events carry an idempotency key, and the meter counts distinct keys per billing period. A retry from your SDK, a redelivery inside our queues, or a replay of a projection all collapse to the single unit you were already charged for. You are billed for what you sent, not for how many times it moved through the system.

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Checking your own usage

Your current billing-period count is on Settings → Usage in the platform. It reflects the same deduplicated count the invoice is built from.

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Retention

The event count and how long events are kept are separate levers. Each plan includes a default retention window; extending it is available on Enterprise plans or with a self-hosted license. See Pricing.