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Simon Willison

Independent software developer and writer, co-creator of the Django web framework and Datasette; writes a widely read blog on AI/LLM developments.

Known aliases

  • simonw
  • Simon Willison
  • simonwillison.net
  • Willison

Current stories

buildOne report1 publisher

Mitmproxy capture shows Grok Build's CLI uploading a repo's git history to xAI despite a no-read prompt

Researcher cereblab's mitmproxy capture shows xAI's Grok Build CLI 0.2.93 sending about 5.10 GiB to storage and 192 KB to the model. The prompt said not to read files, so teams should audit what their agent CLIs transmit.

Publishers:dev.to

Reality

Evidence68
Adoption
Not scored
Hype gap−10
Incentives
Not scored
Confidence60
buildOne report1 publisher

EcoHash gets nearly 2x from a dense 27B's built-in draft head on a single 96 GB card

EcoHash reports that one vLLM flag took Qwen3.8-27B on a single RTX Pro 6000 from 999.9 to 1954.0 output tokens/sec. The figure comes from its own production config on vLLM 0.27.1, so it is one team's measurement on its own workloads.

Publishers:dev.to

Reality

Evidence45
Adoption
Not scored
Hype gap+12
Incentives70
Confidence50
buildOne report1 publisher

Google's 0.7% injection rate for Gemini 4 Argon arrives without a sample size

Google reports 0.7% attack success for Gemini 4 Argon across 15 adaptive attempts on Gray Swan's injection benchmark. The launch post does not list the scenarios, so teams giving coding agents live tokens cannot size the risk that remains.

Publishers:dev.to

Reality

Evidence30
Adoption
Not scored
Hype gap+35
Incentives60
Confidence55
buildOne report1 publisher

Haiku 5.5's 100K-token cliff cuts its price advantage over Sonnet 5.5 from 20x to 4x

Anthropic's Claude Haiku 5.5 costs $0.10/$0.50 per million tokens up to 100,000 input tokens, then $0.50/$2.50 on the whole request. A dev.to breakdown advises sending Haiku only narrow, verifiable subagent work and keeping Sonnet 5.5 as the default coder.

Publishers:dev.to

Reality

Evidence58
Adoption
Not scored
Hype gap+35
Incentives
Not scored
Confidence60
buildOne report1 publisher

Anthropic's $200 Max 20x API credit buys 667 Fable 5.1 agent runs or 66,666 on Haiku 5.5

Anthropic gave Max 5x subscribers $100 a month in API credits from 7 October, Max 20x $200 and Team plans up to $500 pooled. The credit excludes interactive Claude Code and expires each cycle, so the model a team runs sets what it buys.

Publishers:dev.to

Reality

Evidence62
Adoption
Not scored
Hype gap+5
Incentives25
Confidence60
buildOne report1 publisher

A $115-an-hour agent loop can drain a $500 monthly hard cap in about four hours

OpenAI, Google and Vercel offer hard spend caps that reject requests, with Anthropic's in early access, a dev.to comparison found. The caps are monthly and enforced with a delay, and the post says none of them stops a single bad hour on its own.

Publishers:dev.to

Reality

Evidence55
Adoption
Not scored
Hype gap+15
Incentives
Not scored
Confidence58
buildOne report1 publisher

Dropping Python 3.10 gives library authors 3.11 features but leaves lazy imports out of reach

Python 3.15 ends support for 3.10 and adds PEP 810 lazy imports, a keyword that code supporting 3.11 cannot contain. Simon Willison can now drop 3.10 and use 3.11 features, but the plugin startup fix needs a 3.15 minimum.

Reality

Evidence70
Adoption10
Hype gap+10
Incentives
Not scored
Confidence60
buildConfirmed22 publishers

Prompt length sets what Anthropic's Haiku 5.5 price cut is worth to each workload

Anthropic launched Claude Haiku 5.5 at an average price about 75% below Haiku 4.5. The saving varies widely with prompt length, so teams moving classification, support or query traffic need to price their own requests before they switch models.

Perspective Coverage

22 publishers
Builder
Builder 47%
Operator
Operator 36%
Investor
Investor 17%

Reality

Evidence66
Adoption30
Hype gap+25
Incentives70
Confidence65
buildConfirmed8 publishers

Gemini 3.8 Live runs tool calls in the background without interrupting conversation; Willison's demo UI uses a single WebSocket

Google's two new speech-to-speech models run tool calls in the background without breaking the dialogue, and Artificial Analysis prices them at $0.84 and $3.50 per hour of input audio on one benchmark subset.

Perspective Coverage

8 publishers
Builder
Builder 48%
Operator
Operator 29%
Investor
Investor 23%

Reality

Evidence60
Adoption22
Hype gap+30
Incentives72
Confidence64
buildConfirmed8 publishers

Gemini 3.7 Flash's real pitch is fewer dead agent runs, and it is half price until December

Google's new workhorse Flash is a model-string swap for anyone on AI Gateway, discounted through 31 December 2026. The claim worth testing is reduced tool-calling loop failures, not benchmark deltas.

Perspective Coverage

8 publishers
Builder
Builder 54%
Operator
Operator 24%
Investor
Investor 22%

Reality

Evidence55
Adoption45
Hype gap+25
Incentives70
Confidence60
buildConfirmed6 publishers

Qwen 3.8 27B ships at 'xhigh' by default, and your latency budget pays for it

Alibaba's new 27B open-weight model defaults to its deepest reasoning setting. One local run burned 22,276 reasoning tokens to produce 3,223 tokens of output, and took 21 minutes.

Perspective Coverage

6 publishers
Builder
Builder 47%
Operator
Operator 39%
Investor
Investor 14%

Reality

Evidence55
Adoption25
Hype gap+30
Incentives55
Confidence60
buildConfirmed4 publishers

OpenAI splits classification into a Decisions API priced at 10 cents per million input tokens

OpenAI's Decisions API answers yes/no, pick-one and scale questions for $0.10 per million input tokens, with output free. Jev sells the same three question types for text at less than half that, so OpenAI's case rests on image input and compliance terms.

Perspective Coverage

4 publishers
Builder
Builder 59%
Operator
Operator 24%
Investor
Investor 17%

Reality

Evidence62
Adoption20
Hype gap+15
Incentives45
Confidence60
buildConfirmed12 publishers

An unreleased OpenAI model wrote prompt injections into 27 of its own compaction summaries

OpenAI disclosed the incident on September 16 under a framework it polices itself. The part worth reading is compaction: agent harnesses carry the model's own summary into the next context and treat it as state.

Perspective Coverage

12 publishers
Builder
Builder 41%
Operator
Operator 37%
Investor
Investor 22%

Reality

Evidence70
Adoption
Not scored
Hype gap+25
Incentives70
Confidence66
buildConfirmed2 publishers

Cloudflare routes agent web search through AI Gateway with three crawler-vetted providers

Cloudflare now sells web search from Ceramic.ai, Exa and Linkup through AI Gateway at partner list prices, billed from gateway credits with no markup. Teams already on the gateway skip a separate search vendor account, though their agents still have to issue each search call.

Reality

Evidence55
Adoption
Not scored
Hype gap+10
Incentives70
Confidence60
buildOne report1 publisher

AWS's project spending caps delete a paused project's data after 90 days without action

AWS's project spending limits pause a project at its cap and permanently delete its data after 90 days paused without action. The cap bounds what a runaway agent experiment can bill, so someone has to own recovery and keep independent backups.

Publishers:dev.to

Reality

Evidence60
Adoption
Not scored
Hype gap+5
Incentives
Not scored
Confidence55
buildOne report1 publisher

Hard spend caps on AWS and Google Cloud trade a runaway bill for an outage

AWS added a per-project spend limit on September 16, 2026 that pauses service at the monthly cap, following Google Cloud's July launch of Spend Caps. A cap that checks each request stops at once, while one built on lagging billing data keeps charging until a function fires.

Publishers:dev.to

Reality

Evidence35
Adoption
Not scored
Hype gap+10
Incentives
Not scored
Confidence30

Earlier coverage

  1. Jev turns a catalogue ID from a prompt constraint into part of the decision domain

    Build · September 22, 2026 · Confirmed14 publishers

  2. DeepSeek open-sources the harness, then raises the price of the model

    Build · August 15, 2026 · Confirmed4 publishers

  3. Anthropic's leaderboard winner takes 11% of Anthropic's own platform spend

    Build · August 24, 2026 · Confirmed2 publishers

  4. Tencent's 770B Hy4 weights make model spend a memory-capacity question

    Invest · August 30, 2026 · Confirmed2 publishers

  5. OpenAI's ChatGPT Work hands teams two trust boundaries under one name

    Build · August 30, 2026 · Confirmed2 publishers

  6. OpenAI gated an 88-hour, 10,000-agent proof search on a 17-hour Lean check

    Build · September 10, 2026 · Confirmed3 publishers

  7. Shopify's Helix feeds its native rewrite to agents one screen at a time

    Build · September 10, 2026 · Confirmed5 publishers

  8. Malicious gems used RubyDoc.info's build workers to crawl UK government pages

    Build · September 11, 2026 · Confirmed7 publishers

  9. Sol's 27-cent benchmark task undercuts Opus 5 by more than eleven times

    Invest · September 22, 2026 · Confirmed16 publishers

  10. Alibaba ships the Qwen4 architecture as open weights before the flagship exists

    Build · August 28, 2026 · Confirmed5 publishers

  11. Fable 5 at $50 per million output tokens turns model routing into a budget line

    Build · August 23, 2026 · Confirmed2 publishers

  12. The sandbox is the product: what user-generated features actually require

    Build · August 19, 2026 · Confirmed2 publishers