A deep dive into SpacetimeDB's TypeScript SDK and how to wire it into a Next.js 15 App Router application for live visitor tracking and realtime features.
3 min readCurrent systems
Active work,
live signals, and writing.
Featured builds, the latest ranked signal, and recent writing — all in one place.
Featured build
MAINFRAME
Open-source bash stdlib for AI agents. Signals systems-level engineering range. Shows open-source authorship.
Pure bash runtime · Agent working memory primitives
Latest ranked signal
inaturalist-clumper 0.1
<p><strong>Release:</strong> <a href="https://github.com/simonw/inaturalist-clumper/releases/tag/0.1">inaturalist-clumper 0.1</a></p> <p>Part of the infrastructure I use for <a href="https://simonwillison.net/2026/May/1/inat-sig
SIMONW · 34m ago · score 68
Publishing system
Building Realtime Apps with SpacetimeDB and Next.js 15
A deep dive into SpacetimeDB's TypeScript SDK and how to wire it into a Next.js 15 App Router application for live visitor tracking and realtime features.
3 min read · spacetimedb · next.js
Open-source ecosystems
Projects I support
Small but important signal: I contribute to and support AI-native developer tooling beyond my own products.
✦ Selected Work
Systems I've Built
Ranked signal feed
Full feed →SIMON· 34m ago↑ HOT
inaturalist-clumper 0.1
68
aidevMIT TR· 48m ago↑ RISING
Musk v. Altman week 3: Musk and Altman traded blows over each other’s credibility. Now the jury will pick a side.
57
researchaiHN· 4h ago↑ HOT
I believe there are entire companies right now under AI psychosis
66
⬆ 301aisystemsVERGE· 1h ago↑ RISING
Xbox is now XBOX
42
techsystemsLOB· 4h ago↑ RISING
LLM generated submissions should be disallowed
62
devsystemsVERGE· 2h ago↑ RISING
YouTube is expanding its AI deepfake detection tool to all adult users
42
techai✦ /now
What I'm Doing
Right Now
Building
ACTIVE
PropertyJunk.com — junk removal SaaS platform
ACTIVE
TaxScout.app — commercial real estate tax optimization
WIP
MAINFRAME — open source bash stdlib expansion
WIP
toddwatts.dev — this site
Reading
01Attention Is All You Need (re-read)
02The Pragmatic Programmer — 2nd ed.
03Designing ML Systems — Chip Huyen
Watching
▶
Andrej Karpathy
Neural nets: Zero to Hero
▶
Lex Fridman
Sam Altman ep.
▶
ThePrimeagen
Rust streams
My Setup
EditorVS Code + Claude Code
AIClaude Sonnet 4.5, Pi
RuntimeBun 1.2
DeployVercel






