Vanilla JavaScript

Install: pnpm add @watchtowerobservability/browser

Initialize

import { init } from "@watchtowerobservability/browser";
init({ endpoint: "https://edge.example", publishableKey: "wtp_...", service: "web" });

Replay and privacy

Replay is off until enabled in project settings or replay.enabled. Default mask level is strict: all text is masked and inputs are never recorded. Per element:

• data-wt-mask masks the element's text.

• data-wt-block removes the element and its subtree from the recording.

• data-wt-unmask re-shows text (only below strict level).

Exclude routes with replay: { excludeRoutes: ["/billing", /^\/admin/] }.

Content Security Policy

Replay chunks are compressed in a worker, and data is sent to your Watchtower edge:

worker-src blob:;
connect-src 'self' https://<your-watchtower-edge>;
script-src 'self';

The recorder chunk (replay.js) is served from your own origin.

Source maps

Use the build plugin so errors resolve to original code. The upload key is a secret API key from WT_API_KEY, never the publishable key. Maps are deleted after upload by default.

Rollup: watchtowerRollup({ api, project }) from @watchtowerobservability/browser/rollup-plugin, or wtctl sourcemaps upload dist/.

Replay, issues and traces

Errors captured by the SDK become issues. An issue links to the replay of the first affected session, and a session's trace_id links to the backend trace. Linking replays to MCP clients is Phase 5.