Keith Williams

Head of Engineering @calcom

[Keith Williams @keithwillcode]

Big congrats to the @useblacksmith team. They’ve built really nice systems for CI.

Crazy fast cache and sticky disks alone can knock off huge % of your CI wall times. Definitely recommend.

[Aditya Jayaprakash @adijayaprakash]

@sequoia is leading our Series C at a $1B valuation.

We started Blacksmith in 2024 to make CI faster and less painful. In January we ran 5 million CI jobs a week. Today it's over 90 million and growing, and we’re still early.

[Keith Williams @keithwillcode]

@andreaskruszaki @calcom @uixmat @SeanBrydon13 @pacovitiello Hell yeah. Excited for you to join.

[Keith Williams @keithwillcode]

@uixmat @shadcn Indeed. It’s happening.

[Keith Williams @keithwillcode]

Pasquale always unreal

[Pasquale Vitiello @pacovitiello]

Just dropped a new set of chat UI components 💬
https://t.co/F6q8xZSdne

[Keith Williams @keithwillcode]

AI is reshaping software engineering into two increasingly distinct paths: product engineers focused on what to build and why, and foundational engineers focused on the deep systems, infrastructure, security, and scale that make it possible.

As AI handles more of the "how," engineers will have to decide where they want to create the most impact.

[Keith Williams @keithwillcode]

@bitares @calcom Indeed. The number of downstream effects of meetings not scheduling correctly is substantial.

[Keith Williams @keithwillcode]

99.92% uptime this year. Highest we've ever had at @calcom , by far. We could ship faster and let users eat the bugs. Some big names in our space do exactly that. But that's just not how we roll anymore. If people are relying on us to run their scheduling, it has to actually work. In fact, I want this number to be 99.99% soon.

[Keith Williams @keithwillcode]

@kurtkalwin @calcom We had a couple lapses in internal processes for reviewing heavy DB hits and firewall changes. Those have since been rectified.

[Keith Williams @keithwillcode]

Happy to see this. We are in a time of transition and the code does still matter.

[shadcn @shadcn]

There will come a time when how code is written won't matter. But for now, I still care that the code looks and reads right.

I'm not ready to let go :)

[shadcn @shadcn]

There will come a time when how code is written won't matter. But for now, I still care that the code looks and reads right.

I'm not ready to let go :)

[Keith Williams @keithwillcode]

Order of the Sinking Star is such an unreal puzzle game

[Keith Williams @keithwillcode]

I've always hated "move fast and break things." It's an excuse for not doing the work right. So why are we constantly okay with breaking things? And with AI there's no excuse left.

[Keith Williams @keithwillcode]

Great to see this

[Anthropic @AnthropicAI]

To secure open-source software, we’re launching OSS Scanner.

We’ll use our frontier models to periodically scan opted-in open-source projects for vulnerabilities, at no cost. Our reports will provide a proof-of-concept, explanation, and suggested fix.

https://t.co/UFFrLUd25U

[Keith Williams @keithwillcode]

I'm a private person. Barely touched social media for years.

Then my brother, a robotics professor, convinced me to start posting. After 20 years in this, if I can share something that actually helps another engineer, why wouldn't I? That's the whole point. I just want to teach.

[Keith Williams @keithwillcode]

AI can accelerate engineering, but you can't build trust by assuming everyone understands everything it generates.

Strong test suites, CI checks, AI and human reviews, and experienced engineers create the guardrails that keep AI-assisted development moving in the right direction, especially for junior teammates still building judgment.

[Keith Williams @keithwillcode]

@peer_rich Got me so good

[Keith Williams @keithwillcode]

Great leaders don't control every task. They create the space for people to think, challenge, and solve problems creatively.

Leadership is about serving your team, being a sounding board, and helping people find the best solutions rather than using the role to control them.

[Keith Williams @keithwillcode]

Love this mindset

[Karri Saarinen @karrisaarinen]

Frantically fixing a confusing product caused by frantic shipping is just more of the same.

Pause and step back. Get the team clear on what you’re building and why. Have clarity to guide the shape, what ships and what doesn’t.

Quality is a way of working, not a cleanup sprint.

[Keith Williams @keithwillcode]

"Bring me solutions, not problems" is the fastest way to kill trust with your engineers. It teaches them to hide problems or show up with half-baked fixes they're scared to be judged on. So bring me the problem. We'll figure out the solution together. That's the job.

[Keith Williams @keithwillcode]

I bet engineering teams who built their systems using DDD are quietly smiling these days as exposing domain capabilities to APIs/MCPs/agents would be a breeze.