Overview

The TypeScript SDK is a family of packages for sending events and structured logs to Tell. Every package is written in TypeScript with full type definitions — plain JavaScript works too.

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Which package do I need?

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Architecture

There are two standalone SDKs for two different runtimes: Browser SDK (@tell-rs/browser) runs in the browser. It has access to window, document, localStorage, navigator, and sendBeacon. It automatically manages device IDs, sessions, page visibility, UTM capture, and client-side context (screen, OS, locale, timezone). Data is collected client-side — rich but user-modifiable. Node.js SDK (@tell-rs/node) runs on the server. It uses HTTP + JSONL for transport, supports gzip, and has zero browser dependencies. Data is collected server-side — trustworthy and tamper-proof. Framework packages (@tell-rs/react, @tell-rs/nextjs, @tell-rs/vue) are thin wrappers around the browser SDK. They connect Tell to framework lifecycle (mounting, unmounting, route changes) and provide idiomatic APIs (hooks, composables, providers). This is why they require @tell-rs/browser as a peer — the framework package handles integration, the browser SDK handles tracking.

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Further reading

Before diving into an SDK guide, you may want to read the global tracking docs first:

• Events & Properties — event types, when to use each, property patterns
• Users & Identity — device IDs, user IDs, the identity model
• Sessions — session lifecycle, timeouts, automatically collected context
• Logs — severity levels, structured data, session correlation
• Audit & Privacy — privacy model, PII redaction, GDPR/CCPA

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Validation rules

These apply to all packages: