Co-Founder @SierraPlatform. Board @OpenAI.
San Francisco, CA
Joined July 2007
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Bret Taylor retweeted
Anon has been acquired by @SierraPlatform.
Thanks @claybavor and @btaylor for betting on us. And deep gratitude to the team, investors and customers who got us here.
Sierra already builds the best agents in the world. Time to make them even better.
Excited to share that Sierra has acquired Anon.
Daniel Mason and team built Anon to help enterprise AI agents securely use websites the way people do, and in doing so have tackled some of the hardest challenges in making agents reliable and secure for enterprises at scale.
Welcome Daniel, Richárd Hruby, and Hardik Patil!
Read more: sierra.ai/blog/sierra-acquir…
I am so proud that Sierra inducted into JPMorganChase Hall of Innovation. Thank you Lori Beer, Larry Feinsmith, and Gill Haus for our partnership and recognition. sierra.ai/blog/jpmorganchase…
Guardian has been keeping its promises to customers since 1860. Now, they're partnering with Sierra so millions of customers can get answers in seconds. Read more about our work together: sierra.ai/customers/guardian
Every quarter at Sierra, we celebrate the end of the quarter with Double Denim Day (or, as some like to call it, Canadian Tuxedo Day) 👖. This Q3, we needed a lot of denim to celebrate the most remarkable quarter in Sierra's 2.5 year history.
We added over $150M ARR this quarter, bringing our total ARR beyond $400M. Remarkably, we added more ARR in one quarter than we had all of last year.
The most exciting thing to me is that our pace is accelerating. It took us six months to double from $100M to $200M ARR, and only five months to double from $200M to $400M ARR.
@claybavor and I are grateful to our customers and proud of the entire Sierra team.
I was and am shocked the exponential time hypothesis is false. I had hoped for a result on P / NP from the models, but had naively presumed they would prove the opposite of this result.
Announcing three major scientific discoveries, one each in mathematics (harmonic analysis), computer science (complexity theory), and physics (quantum field theory).
AI starting to help us improve our understanding of the universe! openai.com/index/building-sc…
Bret Taylor retweeted
Over the past several months, we have substantially hardened the security of our research training environment. We’ve removed live internet access for all frontier models during training and built an offline world for them to use instead—a cached version of the web where they can still learn to browse, search, and use applications.
On September 20, after a model exploited a DNS misconfiguration to find a way outside of this offline world, we paused frontier training to strengthen containment further. We assembled teams of agents, powered by our most cyber-capable models, and tasked them with finding weaknesses in our research environments.
While they found no route to the internet they could easily exploit while concealing their activity from our monitors, they did find zero-day vulnerabilities, virtual machine escapes, and hardware side-channels for communication between agents. We used their discoveries to further strengthen our defenses and contribute fixes to open-source software.
After strengthening our containment architecture, we resumed our frontier RL training and inference on October 1. We’ve reserved substantial compute for continuous red-teaming, and made high-compute red-teaming part of the safety cases we use to decide whether frontier training and evaluation can proceed securely.
openai.com/index/securing-ou…
300+ people at Sierra Summit in EMEA. We had wide-ranging conversations with Alan Stott, COO @ VM02, and Stuart Riley, Group CIO @ HSBC about the importance of bringing employees along on the AI journey.
Bret Taylor retweeted
built myself a little demo of the new Personal Agent Protocol (Poppy)
using Pi Durable, deployed to Cloudflare ofc
ask it to exchange order #1042
poppy-caller.roundtrip.worke…
github.com/irvinebroque/popp…
On Tuesday, Sierra announced Personal Agent Protocol with Meta, Genesys, Instinct, Rocket, Shopify, Stripe, and Walmart. The response has been incredible and today we’re publishing the first draft of the protocol at personalagentprotocol.org and announcing 35 new design partners.
As personal agents take on more, our goal is simple: consumers have choice and control, and companies know when they’re dealing with an agent and who it represents.
This draft is a starting point. We’d love for companies, developers, and personal agent builders to read it, give feedback, and help us build an open standard together.
Personal Agent Protocol got a lot of attention earlier this week. Here is Alex McGillis from Rocket doing a live demo of it in action - Muse directly communicating with the Rocket agent, discovered, authenticated, and governed by PAP
Watch the Personal Agent Protocol in action. @Redfin and @RocketOTD agents working with Muse to find homes in Michigan and get a user pre-approved for a mortgage. Thank you to Alex McGillis for a great demo.
To complement the Personal Agent Protocol, Sierra has developed the Fleming-1 model, which detects when the caller on the other side of a phone call is an AI sierra.ai/blog/caller-id-in-…
Bret Taylor retweeted
We’re releasing a broad range of new mathematical results produced by an internal frontier model.
We’ve been consulting with the independent Advisory Group on Mathematics and Artificial Intelligence at the Institute for Advanced Study, and we have drawn on their advice and public recommendations to inform how we release these results.
github.com/openai/math
Manat started as an intern, and now she's an engineer building our voice products. She did an amazing demo of Tandem Voice and Persona Studio today. Here we are celebrating with her parents after the keynote.
There's only one thing better than using Ghostwriter, and that's watching our head of sales engineering, Kaila Fleisig demo it
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It was awesome to see @letsleverup demo Horizon on stage to over a thousand people this morning. So grateful you and the Takeoff team decided to join Sierra, Aakash
Today we’re announcing Personal Agent Protocol — an open standard @Meta and @SierraPlatform are developing along with industry partners at @Genesys, @instinct, @RocketOTD, @Shopify, @stripe, and @Walmart. It will help define how personal agents interact with businesses and is open for anyone to implement. You can read more here - and if anyone is interested in joining let me know! sierra.ai/blog/introducing-p…
More from @Kr00ney: cnbc.com/2026/10/06/meta-joi…
