Simon Willison

What blog posts influenced your thinking the most?

Simon Willison reflects on three blog posts that shaped his professional outlook: Joel Spolsky’s *The Law of Leaky Abstractions*, Will Larson’s 2018 article *Migrations: the sole scalable fix to tech debt*, and Charity Majors’ *The Engineer/Manager Pendulum*. Each piece offered a distinct lesson—recognizing hidden complexities in abstractions, embracing migrations as a core engineering skill, and validating the fluid movement between engineering and management roles. These insights collectively encouraged Willison to deepen his technical understanding, prioritize migration work, and feel empowered to shift career tracks without fear.

Simon Willison
Sep 11

Feeling sad about AI

Simon Willison reflects on the emotional impact of AI tools that can produce code quickly, noting that many developers experience an initial sense of disheartenment. He argues that recognizing the shift from coding to higher‑level problem solving allows experienced engineers to leverage new tools and add greater value. Willison emphasizes that software engineering has always faced rapid change, so adapting to AI is part of the profession’s ongoing evolution.

Simon Willison
Sep 14

Quoting Laurie Voss

Laurie Voss argues that while the cost of writing code has fallen dramatically, the costs of reviewing, fixing, and operating software are rising and will continue to do so. She emphasizes that the true expense lies in understanding user needs, precisely defining requirements, and ensuring a pleasant user experience—costs that are unique to each software product and do not scale with reuse. As software demand grows without an upper limit, these user‑centric costs will dominate the overall development effort.

Simon Willison
Sep 6

There's No Limit to How Bad Code Can Get

Simon Willison discusses the pitfalls of attempting to replace a legacy system with a new one when technical debt is overwhelming. He explains that while the old system continues to evolve, developers lack incentive to improve it, and the new team, initially fast, eventually struggles to understand and deliver the required functionality. The result is often two partially functional systems in production, with the new one abandoned and the old one still running, increasing risk and complexity.

Simon Willison
Sep 14

The contagion of fear

The article discusses Bryan Cantrill’s response to a tweet by former Anthropic employee Jacob Coxon, who claimed that AI could kill humanity by the end of the decade. Cantrill shares a personal anecdote about how his own youthful mistakes caused undue panic among non‑technical peers and warns against repeating that pattern. He emphasizes that domain experts must be cautious when making alarmist claims, especially about complex topics like critical infrastructure, bioweapons, and extinction, and that the burden of accurate information lies with those making such statements.

Simon Willison
5d ago

How To Write With An LLM

The article "How To Write With An LLM" by Thomas Ptacek explains how to use large language models (LLMs) as copyeditors rather than writing assistants. Ptacek advocates a strict rule: never use any single word or phrase suggested by an LLM, treating it as intellectual personal protective equipment. He shares his own practice of using LLMs for fact‑checking, spelling, grammar, and occasional thesaurus help, and provides a screenshot of his personal LLM copyediting tool along with a prompt to help readers build their own.

Simon Willison
6d ago

Claude Cowork and chat are now one Claude

Claude Cowork and the standard chat interface are merging into a single Claude experience, allowing users to hand over tasks or ask quick questions that the system will continue to handle even after the laptop is closed. The rollout will begin with Pro and Max plan users across web, desktop, and mobile, and will extend to new users on these plans over the coming weeks. This integration suggests Claude is evolving into a general agent, simplifying the distinction between Cowork and regular Claude usage.

Simon Willison
Aug 19

Quoting Jeremy Morrell

My hypothesis is that there is a new opportunity for Extensible Software on the web . LLMs radically lower the cost of authoring extensions, and modern sandbox primitives lower the deployment cost and provide good security boundaries.

Simon Willison
Aug 23

Quoting Drew Breunig

The article reflects on the shift in perspective after the release of Fable, a new model that promised to solve many coding challenges at a comparable or lower cost. Prior to Fable, developers felt it was pointless to invest heavily in coding tools or context strategies, as newer models would likely render them obsolete. However, Fable’s performance was so impressive that, despite its high cost, it prompted a reevaluation of how work was distributed across different models such as Opus, 5.6, K3, and GLM.

Simon Willison
Sep 11

Quoting Boris Cherny

The article discusses how production code generated by Claude, Anthropic’s AI, should meet higher standards than human-written code. Anthropic enforces this through numerous guardrails such as lint rules, extensive testing, Claude-driven end‑to‑end tests, daily fuzzers, automated code and security reviews, and automated refactoring. These measures aim to prevent the code from becoming difficult to maintain.

Simon Willison
Sep 12

Quoting Paul Ford

Simon Willison reflects on the evolving role of software developers in the age of AI, noting that while AI can produce high‑quality code, it also enables poor execution that leads to project failures. He argues that the industry is beginning to recognize the continued need for human collaboration and expertise to truly innovate. The piece highlights the tension between automation and the essential human element in software creation.