otap

Local observability TUI — tap into Datadog traces, OpenTelemetry spans, and Sentry errors right in your terminal.

Single command. No config. Starts receivers, renders a TUI, tears down on exit.

Quick Start

# Via brew
brew tap schester44/tap
brew install otap
otap

# Or run from source
./bin/otap

# Start your app — dd-trace already defaults to localhost:8126
DD_API_KEY=local SENTRY_DNS=http://key@localhost:8137/1 yarn start

# Or with OpenTelemetry
OTEL_EXPORTER_OTLP_ENDPOINT=http://localhost:4318 node --import ./instrument.mjs app.js

What It Does

Embeds three HTTP receivers and a terminal UI in a single process:

• Datadog receiver (:8126) — accepts dd-trace msgpack payloads (/v0.3/traces, /v0.4/traces, etc.). Uses the default DD Agent port so no extra config needed.
• OTLP receiver (:4318) — accepts OpenTelemetry HTTP trace exports (/v1/traces). Works with any @opentelemetry/exporter-trace-otlp-http SDK.
• Sentry receiver (:8137) — accepts @sentry/node envelope payloads (/api/{id}/envelope/)
• TUI — OpenTUI React app with trace waterfall, span inspection, error viewer, keyboard navigation

Use --drop to filter noisy spans by resource pattern.

Keyboard

Key	Action
↑↓ / jk	Navigate list
enter	Inspect span tags/meta/metrics
esc	Back to trace list
Tab	Switch Traces ↔ Errors
s / S	Cycle service filter forward/backward
←→ / hl	Scroll detail pane
PgUp/PgDn	Jump 10 items
Space	Pause/resume
x	Clear all data
Ctrl+C	Quit

Filtering Noisy Spans

Drop spans matching a resource substring with --drop:

otap --drop health_check --drop "SELECT 1"

Multi-Service Support

Captures traces from all instrumented apps on your machine (any app sending to localhost:8126). Press s to cycle through discovered services as a filter.

CLI

otap doubles as a CLI for querying data from a running instance. Output is JSON — pipe to jq or use from scripts and AI agents.

otap summary                       # trace/error/service counts
otap services                      # list discovered services
otap traces                        # recent traces
otap traces --service risk-api     # filter by service
otap traces --limit 10             # limit results
otap trace TRACE_ID                # single trace with all spans
otap errors                        # recent errors
otap errors --level error          # filter by level
otap clear                         # wipe stored data
otap help                          # full usage

Configuration

Env Var	Default	Description
DD_PORT	8126	Datadog receiver port
OTLP_PORT	4318	OTLP/HTTP receiver port
SENTRY_PORT	8137	Sentry receiver port

Requirements

• Bun — dependencies auto-install on first run