Brian Casel
@briancasel.com
Pinned
Brian Casel
@briancasel.com
· Aug 25
Agent OS | A free open-source system to train smart AI coding agents
Agent OS is a free open-source system to train your AI coding agents to build your way, not their way. Works with Claude Code, Cursor, or any other AI coding tool.
buildermethods.com
6 weeks ago I released Agent OS. Today it's at 1000+ stars on GitHub :)
Already shipped many improvements. So many more planned. It's just getting started!
Today I dropped an all-new walkthrough video. buildermethods.com/agent-os
Already shipped many improvements. So many more planned. It's just getting started!
Today I dropped an all-new walkthrough video. buildermethods.com/agent-os
Started hacking on something new. Can't wait to share.
November 26, 2025 at 1:38 AM
Started hacking on something new. Can't wait to share.
How do I make my Apple Watch never talk to me again ever?
Especially during workouts.
Especially during workouts.
November 25, 2025 at 1:19 PM
How do I make my Apple Watch never talk to me again ever?
Especially during workouts.
Especially during workouts.
There are still (and always will be) world-class, experienced, highly technical, creative thinkers behind the world's best automobiles.
But those people are not assembling the cars by hand.
Robots do that.
But those people are not assembling the cars by hand.
Robots do that.
November 21, 2025 at 8:37 PM
There are still (and always will be) world-class, experienced, highly technical, creative thinkers behind the world's best automobiles.
But those people are not assembling the cars by hand.
Robots do that.
But those people are not assembling the cars by hand.
Robots do that.
Gmail's filters have been broken for years.
So I built filterhawk.com — Plug it into Gmail and take back control of your inbox with better, intuitive filters that work the way you'd expect.
Here's how it fixes Gmail's (broken) filters: 👇
So I built filterhawk.com — Plug it into Gmail and take back control of your inbox with better, intuitive filters that work the way you'd expect.
Here's how it fixes Gmail's (broken) filters: 👇
November 19, 2025 at 2:46 PM
Gmail's filters have been broken for years.
So I built filterhawk.com — Plug it into Gmail and take back control of your inbox with better, intuitive filters that work the way you'd expect.
Here's how it fixes Gmail's (broken) filters: 👇
So I built filterhawk.com — Plug it into Gmail and take back control of your inbox with better, intuitive filters that work the way you'd expect.
Here's how it fixes Gmail's (broken) filters: 👇
interesting timing for customer experience outreach
November 18, 2025 at 7:17 PM
interesting timing for customer experience outreach
Product builders & dev teams — I'm hosting a live workshop for this Wednesday on the shift to autonomous coding agents.
How we got here and key skills to focus on going forward.
Grab a seat or share with your team: buildermethods.com/workshops/au...
How we got here and key skills to focus on going forward.
Grab a seat or share with your team: buildermethods.com/workshops/au...
Building with Autonomous Agents
Builder Methods is a site that helps software developers build better software, faster by leveraging AI. Created by Brian Casel.
buildermethods.com
November 17, 2025 at 8:22 PM
Product builders & dev teams — I'm hosting a live workshop for this Wednesday on the shift to autonomous coding agents.
How we got here and key skills to focus on going forward.
Grab a seat or share with your team: buildermethods.com/workshops/au...
How we got here and key skills to focus on going forward.
Grab a seat or share with your team: buildermethods.com/workshops/au...
Reposted by Brian Casel
Decided to YOLO and let anyone join us on our @thepanel.bsky.social livestream, and the founder of @riversidefm.bsky.social (Nadav Keyson) joined @briancasel.com and I. ;)
November 13, 2025 at 8:51 PM
Decided to YOLO and let anyone join us on our @thepanel.bsky.social livestream, and the founder of @riversidefm.bsky.social (Nadav Keyson) joined @briancasel.com and I. ;)
It's podcast day. Hang with @justinjackson.ca and me live, 30 mins from now.
Topics:
- Future of The Panel (feedback please)
- ChatGPT booked my vacation
- Who's my competition?
- Rails new'd a new app.
- Risky launches
- I raised prices and then...
www.youtube.com/live/HhfG2dT...
Topics:
- Future of The Panel (feedback please)
- ChatGPT booked my vacation
- Who's my competition?
- Rails new'd a new app.
- Risky launches
- I raised prices and then...
www.youtube.com/live/HhfG2dT...
THE PANEL PODCAST – live with Justin Jackson and Brian Casel
YouTube video by Justin Jackson
www.youtube.com
November 13, 2025 at 7:38 PM
It's podcast day. Hang with @justinjackson.ca and me live, 30 mins from now.
Topics:
- Future of The Panel (feedback please)
- ChatGPT booked my vacation
- Who's my competition?
- Rails new'd a new app.
- Risky launches
- I raised prices and then...
www.youtube.com/live/HhfG2dT...
Topics:
- Future of The Panel (feedback please)
- ChatGPT booked my vacation
- Who's my competition?
- Rails new'd a new app.
- Risky launches
- I raised prices and then...
www.youtube.com/live/HhfG2dT...
My next live workshop is on the current shift to building with autonomous agents.
Live Nov 19. Recording will be available. Grab a seat, bring you team.
buildermethods.com/workshops/au...
Live Nov 19. Recording will be available. Grab a seat, bring you team.
buildermethods.com/workshops/au...
Building with Autonomous Agents
Builder Methods is a site that helps software developers build better software, faster by leveraging AI. Created by Brian Casel.
buildermethods.com
November 11, 2025 at 2:22 PM
My next live workshop is on the current shift to building with autonomous agents.
Live Nov 19. Recording will be available. Grab a seat, bring you team.
buildermethods.com/workshops/au...
Live Nov 19. Recording will be available. Grab a seat, bring you team.
buildermethods.com/workshops/au...
9 months ago: Claude Code was not a thing yet.
November 10, 2025 at 4:39 PM
9 months ago: Claude Code was not a thing yet.
Every email client product is way too opinionated.
And I hate all of their opinions.
And I hate all of their opinions.
November 5, 2025 at 5:23 PM
Every email client product is way too opinionated.
And I hate all of their opinions.
And I hate all of their opinions.
3 sales in the first 24 hours after raising prices. 😍
November 3, 2025 at 5:50 PM
3 sales in the first 24 hours after raising prices. 😍
Cursor—a tool company—getting into the model game is super interesting.
Purpose-built LLMs that are far superior at the job-to-be-done of the tool is a trend I'm sure we haven't seen the last of—especially from makers of tools for builders/creators.
Purpose-built LLMs that are far superior at the job-to-be-done of the tool is a trend I'm sure we haven't seen the last of—especially from makers of tools for builders/creators.
November 3, 2025 at 3:24 PM
Cursor—a tool company—getting into the model game is super interesting.
Purpose-built LLMs that are far superior at the job-to-be-done of the tool is a trend I'm sure we haven't seen the last of—especially from makers of tools for builders/creators.
Purpose-built LLMs that are far superior at the job-to-be-done of the tool is a trend I'm sure we haven't seen the last of—especially from makers of tools for builders/creators.
First work session in my new Airpods Max. Not loving the weight and tight feel for a long session. Will they "break in"?
Loved my Sony WH-1000xm5 the past few years, except that they get warm on long sessions.
What's your favorite over-ear headphones?
Loved my Sony WH-1000xm5 the past few years, except that they get warm on long sessions.
What's your favorite over-ear headphones?
November 2, 2025 at 4:11 PM
First work session in my new Airpods Max. Not loving the weight and tight feel for a long session. Will they "break in"?
Loved my Sony WH-1000xm5 the past few years, except that they get warm on long sessions.
What's your favorite over-ear headphones?
Loved my Sony WH-1000xm5 the past few years, except that they get warm on long sessions.
What's your favorite over-ear headphones?
The story of how we create with AI is still unfolding.
First, it made our old workflows faster. But now the good part: fundamentally rethinking what our workflows should be.
First, it made our old workflows faster. But now the good part: fundamentally rethinking what our workflows should be.
October 31, 2025 at 8:01 PM
The story of how we create with AI is still unfolding.
First, it made our old workflows faster. But now the good part: fundamentally rethinking what our workflows should be.
First, it made our old workflows faster. But now the good part: fundamentally rethinking what our workflows should be.
The speed of Cursor's new Composer model is unreal.
October 31, 2025 at 1:24 PM
The speed of Cursor's new Composer model is unreal.
It's panel day - going live in an hour. Come hang! www.youtube.com/live/dKrjclI...
THE PANEL PODCAST – live with Justin Jackson and Brian Casel
Come hang out and chat while we record!
Topics:
- Distinct phases of a startup in year 1.
- Building a marketing website with V0
- Brand loyalties. (Example: OpenAI vs Anthropic)
- Derek Sivers' "pl...
www.youtube.com
October 30, 2025 at 6:17 PM
It's panel day - going live in an hour. Come hang! www.youtube.com/live/dKrjclI...
Reposted by Brian Casel
I've been using @briancasel.com's AgentOS to build a little workout/fitness tracker (the mid-life todo list every one builds). The way it layers up from a high-level product vision to a roadmap to feature specs to tasks really seems to improve the quality of the code.
buildermethods.com/agent-os
buildermethods.com/agent-os
Agent OS | The system for spec-driven development with AI coding agents
Agent OS is a popular system spec-driven development with AI coding agents. It's a free open-source framework from Builder Methods, created by Brian Casel.
buildermethods.com
October 29, 2025 at 11:35 AM
I've been using @briancasel.com's AgentOS to build a little workout/fitness tracker (the mid-life todo list every one builds). The way it layers up from a high-level product vision to a roadmap to feature specs to tasks really seems to improve the quality of the code.
buildermethods.com/agent-os
buildermethods.com/agent-os
I wish all AI models/tools would train me on whether I chose the best model for a given task.
After the 1st prompt, a sidebar message like "based on your request, we think our other model (name) would give you a better result than the one you're using."
After the 1st prompt, a sidebar message like "based on your request, we think our other model (name) would give you a better result than the one you're using."
October 28, 2025 at 8:10 PM
I wish all AI models/tools would train me on whether I chose the best model for a given task.
After the 1st prompt, a sidebar message like "based on your request, we think our other model (name) would give you a better result than the one you're using."
After the 1st prompt, a sidebar message like "based on your request, we think our other model (name) would give you a better result than the one you're using."
If you're serious about YouTube we have a private telegram group to where we talk YT game.
If you want in, send me your YT channel and your telegram username.
Only requirement is you've published at least 5 videos in the past 5 months and plan to publish more.
If you want in, send me your YT channel and your telegram username.
Only requirement is you've published at least 5 videos in the past 5 months and plan to publish more.
October 28, 2025 at 7:17 PM
If you're serious about YouTube we have a private telegram group to where we talk YT game.
If you want in, send me your YT channel and your telegram username.
Only requirement is you've published at least 5 videos in the past 5 months and plan to publish more.
If you want in, send me your YT channel and your telegram username.
Only requirement is you've published at least 5 videos in the past 5 months and plan to publish more.
Watched 'A House Full of Dynamite' this weekend. Intense. Great acting.
October 27, 2025 at 7:21 PM
Watched 'A House Full of Dynamite' this weekend. Intense. Great acting.
Experimenting with AI support in the Clarityflow help widget. Customers can choose to chat with AI or send an email. Agent is trained on our support docs.
Early findings:
Early findings:
October 27, 2025 at 3:49 PM
Experimenting with AI support in the Clarityflow help widget. Customers can choose to chat with AI or send an email. Agent is trained on our support docs.
Early findings:
Early findings:
Looking for examples of interview shows that present well on youtube, with thoughtful editing and care for viewer's experience.
Especially where guest is sharing screen, showing and telling.
Especially where guest is sharing screen, showing and telling.
October 24, 2025 at 3:55 PM
Looking for examples of interview shows that present well on youtube, with thoughtful editing and care for viewer's experience.
Especially where guest is sharing screen, showing and telling.
Especially where guest is sharing screen, showing and telling.
The early creative process when planning a new youtube video.
October 23, 2025 at 9:54 PM
The early creative process when planning a new youtube video.
Who's hanging out today?
A few more topics on the docket:
- Projects that generate (unwanted) jobs
- Building stuff on camera is hard
- Wealth freedom & monetizing ideas
A few more topics on the docket:
- Projects that generate (unwanted) jobs
- Building stuff on camera is hard
- Wealth freedom & monetizing ideas
Join us for our live recording in ~1 hour:
youtube.com/live/glJHGTH...
- @justinjackson.ca goes to high school
- "The great relief of wealth is the freedom from having to dream of monetizing every successful idea or creation."
- @briancasel.com's workshop (Justin went - what were his thoughts?)
youtube.com/live/glJHGTH...
- @justinjackson.ca goes to high school
- "The great relief of wealth is the freedom from having to dream of monetizing every successful idea or creation."
- @briancasel.com's workshop (Justin went - what were his thoughts?)
THE PANEL PODCAST – live with Justin Jackson and Brian Casel
YouTube video by Justin Jackson
youtube.com
October 23, 2025 at 6:26 PM
Who's hanging out today?
A few more topics on the docket:
- Projects that generate (unwanted) jobs
- Building stuff on camera is hard
- Wealth freedom & monetizing ideas
A few more topics on the docket:
- Projects that generate (unwanted) jobs
- Building stuff on camera is hard
- Wealth freedom & monetizing ideas