About Tejas Kumar
Berlin / AI Engineer at IBM
The short version, the long version, and everywhere else Tejas Kumar is online.
Who is Tejas Kumar?
Tejas Kumar is an AI Engineer at IBM, based in Berlin, Germany. He has been building on the web for over 25 years, and before IBM he worked at Spotify, G2i, Vercel, Xata as Director of Developer Relations, and DataStax, which IBM acquired. He is the best selling author of Fluent React, published by O'Reilly (ISBN 9781098138714), a book about how React works internally. He hosts ConTejas Code, a weekly long form podcast with 98 episodes. He has given 82 recorded talks at 66 events, starting with a TEDxYouth talk in Doha in 2012 called "Papercuts Can Kill" and speaking at conferences since 2018. He is also an angel investor and advisor to early stage startups, 3 of the 6 he has backed since acquired, by CoreWeave, the Linux Foundation and Supabase, and he backs early stage founders with money, with advice, or with both.
What does Tejas Kumar do at IBM?
Tejas Kumar is an AI Engineer at IBM, based in Berlin. His public work is AI engineering: large language models, retrieval augmented generation, the Model Context Protocol, small language models and multi agent systems, all of which appear in the talks he gave between 2024 and 2026. He joined IBM through its acquisition of DataStax.
His talk Harnesses in AI: A Deep Dive at AI Engineer Europe 2026 builds an agent harness live, and he wrote the same material up as What Is an Agent Harness?, with the code for every step.
Where is Tejas Kumar based?
Tejas Kumar lives and works in Berlin, Germany, and has worked in Germany since 2015. He travels from Berlin for conferences and has spoken at 66 events across Europe, North America, Asia and Africa.
Is this the same Tejas Kumar as the Rice University researcher?
No. Several people share the name. The Tejas Kumar on this page is the AI Engineer at IBM in Berlin who wrote Fluent React for O'Reilly and hosts ConTejas Code, and he is not the Tejas Kumar who publishes research at Rice University. His Wikidata item is Q114756295.
What has Tejas Kumar worked on?
He has been building on the web for over 25 years. Newest first:
- IBMAI Engineer, current
- DataStaxAcquired by IBM
- IndependentDeveloper relations consultancy
- XataDirector of Developer Relations
- SpotifyStaff Engineer
- G2iEngineering Lead
- VercelHead of Developer Relations
- ContiamoSenior Frontend Engineer, 2017 to 2019
- McMaklerFrontend Engineer, 2015 to 2017
- GrowDigital Lead, 2013 to 2015
What has Tejas Kumar made?
- Fluent ReactA book on how React works inside, published by O'Reilly.
- ConTejas CodeA weekly long form podcast, 98 episodes.
- Conference talks82 recorded talks at 66 events since 2012.
- What Is an Agent Harness?His guide to agent harnesses and harness engineering, built from his AI Engineer Europe 2026 talk, with code for every step.
- The blogEssays he has been writing since 2020.
- DewfallAn app for reading the whole Bible, one verse at a time, with the commentary and the original languages next to the text.
- PrayingPeopleAn app for praying together: share a request with your church, your small group or two friends, and see who prayed.
Tejas Kumar has severe hemophilia A and writes about it himself in Health, Fitness, DevRel, and Hemophilia. The full first hand account of his life, from the diagnosis at 3 months to Berlin, is his story.
He is a Christian and is available to preach: a sermon from the Bible, with the things he has lived through as the illustration rather than the subject. He became a Christian at 15 and has served in his church as a youth leader, a worship leader, a men's ministry leader, a deacon and in care ministry. Churches, church conferences, camps and youth events are welcome to ask.
Does Tejas Kumar invest in startups?
Yes. Tejas Kumar is an angel investor in early stage startups, sometimes writing a check and sometimes coming in as an advisor instead. He has backed 6 companies so far and 3 of them have been acquired. He writes small checks, usually alongside Guillermo Rauch, David Khourshid and Swyx, and founders looking for angel investors can book a pitch call with him.
- OpenPipeInvestorReinforcement learning that trains AI agents to get better at the job.Acquired 2025CoreWeaveNASDAQ: CRWV
- OpenSaucedInvestorIntelligence on who actually builds open source, and how.Acquired 2024The Linux Foundation
- OrioleDATAAdvisorA storage engine that makes Postgres several times faster on modern hardware.Acquired 2024Supabase
- CrabNebulaInvestorThe company behind Tauri's app distribution, updates and security audits.$7.5M seed led by OSS Capital, 2023
- RavionInvestorAWS infrastructure that deploys itself, built for engineers and their agents.Y Combinator, W22
- ContendaAdvisorTurned recorded talks and streams into written developer content.
Where can you find Tejas Kumar online?
These are all of his accounts. Anything else using his name is not him.
What do people say about Tejas Kumar?
Six posts from people he has worked with, spoken alongside, or taught. They are quoted exactly as written.
I love meeting up with @tejaskumar_ at conferences. We always try to find a special time to have a little devotional and prayer meeting together. He's wonderful!
Aug 18, 2023View onHad an awesome time catching up with @tejaskumar_ at the office today π
Y'all should go follow him if you haven't already π₯
Jul 11, 2023View onThe amount of things Iβve learned from @tejaskumar_ on DevRel in the past few months are gold, you donβt get this anywhere.
Oct 24, 2023View onGrabbed an opportunity to meet the super inspiring @tejaskumar_ today.
The one message that stuck with me from his journey - βLife has plans for youβ.
Been following him for more than two years, I feel so thankful to have met him today!
β
PS: Forgot to click a selfie π
Jul 11, 2023View onIt is always a soul-filling chat with @tejaskumar_! I am grateful to have him on the fireside chat earlier this December, discussing the human side of tech and devrel, along with his daily life-threatening struggles.
Tejas, your unwavering perseverance is a beacon of inspirationDec 30, 2023View on
How do you get in touch with Tejas Kumar?
Email is the fastest way, and every message reaches him. He is based in Berlin, Germany, and answers in English.
If this is about booking Tejas Kumar to speak, the speaking page has the topics, the formats, and a bio you can paste straight into a program. If it is about teaching a team rather than addressing a room, the workshops page has the two he teaches, what they cost, and how to book one.