telemetry.dev

说明（暂未翻译，以下为英文原文）

Observability for AI/LLM apps built on OpenTelemetry. Traces model calls and tool steps with tokens, cost, latency and errors; send OTLP over HTTP from any language or use the TypeScript SDKs. Free plan includes 10,000 spans/month, 7-day retention, 1 project and 2 seats, no credit card.