Simon Willison Builds iNaturalist Sightings App Using Claude Code

Simon Willison created a web app called iNaturalist Sightings to view his iNaturalist observations from two accounts grouped by time and location. He built the entire project on his phone using Claude Code for web while camping. First, he developed a Python CLI tool called inaturalist-clumper to fetch and "clump" observations, defaulting to clumps within 2 hours and 5km of each other. Then he set up a Git scraping repository (simonw/inaturalist-clumps) to run the tool and record results to clumps.json, hosted on GitHub for CORS access. Finally, he prompted his simonw/tools repo to build inat-sightings.html, which fetches the JSON and displays observations with thumbnails using small.jpg URLs with lazy loading, and opens large.jpg in an HTML modal on click. The app shows common species names when available. Willison posted about this on 1st May 2026, offering a curated email digest of LLM developments for $10/month sponsors.