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This tutorial builds Linkly, a link shortener, one worker at a time. You start with a single function that turns /s/abc into a redirect, and finish with a multi-tenant link platform that has durable execution, storage, analytics, a live click stream, bulk imports, and permission gated untrusted browser workers that have all the same functionality and observability as the base system. Each chapter adds one capability by adding a worker to your existing system. The point is not the link shortener itself, but the pattern: a real system on iii is a set of small workers that invoke each other’s functions and triggers. You add capability without needing to refactor existing functionality.
New to iii? Install it before you begin.

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Choose your path

Both paths will build the same system.
  • Agentic gives an AI agent one prompt per chapter and reviews what it writes.
  • Exploration writes each chapter by hand, with the reasoning behind every step.

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An overview of the chapters

The agentic path contains all of these chapters on a single page while the exploration path divides them into separate sections.

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Ch. 1: Foundations

Build a custom link worker with link::create and link::resolve, store links in memory, then expose them over HTTP with http as POST /links and GET /s/:code.

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Ch. 2: Observe everything

Use the engine-injected iii-observability functions for logs and traces, and open the console to inspect functions, triggers, and live invocations.

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Ch. 3: Persist everything

Add a database worker (SQLite) so links and click events are stored durably and survive restarts, with state kept in front as a fast read cache.

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Ch. 4: Make it durable

Push click events onto queue so redirects stay fast, and publish link.created events with pubsub that a cache and an analytics function each subscribe to.

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Ch. 5: Stream live clicks

Push every click to subscribers in real time from a dedicated click-streamer worker with iii-stream.

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Ch. 6: Move bulk data with channels

Bulk-load links from a CSV in a single streamed upload over a channel.

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Ch. 7: Bring in the browser

Turn a browser tab into a worker with the browser SDK: invoke link::create directly, subscribe to the click stream, and register a browser-side function the server can call.