Simon Willison September 12, 2026

Generating running routes with GPT-6 Astra and ChatGPT Work

Simon Willison demonstrates how ChatGPT Work with GPT‑6 Astra can generate 5K and 10K running routes that loop from a specified address using OpenStreetMap data. The system produced an embedded visualization and downloadable GPX and GeoJSON files, and explained that it used Nominatim, Overpass, and local calculations to create the routes. However, the actual Python code used was not accessible due to thread compaction, highlighting a transparency issue in LLM systems that compact conversation history.

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Simon Willison

Sep 1

GeoJSON Map Viewer

Simon Willison describes a GeoJSON Map Viewer tool he helped build to display local political boundaries for the Granada Community Services District and the Midcoast Community Council. The tool was created through iterations using Claude Code for web and Fable 5.1, and it allows users to export the map as a PNG. The boundaries were sourced from government data via ChatGPT Work, and a link shows both polygons displayed simultaneously on the viewer.

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Simon Willison

Aug 15

CORS Chat

Tool: CORS Chat I built this today ( with GPT-5. 6-Sol xhigh ) to help test Qwen 3.

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Simon Willison

Sep 7

Mercator ↔ Equal Earth

Simon Willison created an animated transition tool that morphs a map from the Mercator projection to the Equal Earth projection using D3. The project was inspired by the recent UN vote on the Equal Earth map projection and was built with GPT‑6 Astra (medium) in ChatGPT Work. It showcases how modern AI and web technologies can visualize complex geospatial transformations.

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Simon Willison

Aug 13

llm-gemini 0.33

Release: llm-gemini 0. 33 It's been a while since the last llm-gemini release.

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Simon Willison

Sep 4

The Pelican comparison grid for Astra is pretty interesting

Simon Willison tested GPT‑6 Astra by generating SVG pelicans riding bicycles at various reasoning levels and compared the results to GPT‑5.6 Sol, Terra, and Luna. The Astra pelicans consistently outperformed the other models, especially at low and xhigh reasoning levels, and even the Astra max version produced high‑quality images. Astra also used fewer tokens and was roughly twice as expensive as Sol, yet its low‑level output was cheaper and superior to any Sol model.

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Simon Willison

Sep 5

Using Blender with coding agents on macOS

Simon Willison demonstrates how to use Blender with coding agents on macOS by installing the full Mac application from blender.org and issuing prompts to ChatGPT Codex. He shows a step-by-step example where the agent renders a scene of a pelican riding a bicycle, then adds background flair and improves the image. The resulting image is generated via Blender's Python API.

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One email a morning, machine-written

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GeoJSON Map Viewer

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Mercator ↔ Equal Earth

llm-gemini 0.33

The Pelican comparison grid for Astra is pretty interesting

Using Blender with coding agents on macOS