Articles and thoughts on software, leadership, and life by Tejas Kumarhttps://tej.as/https://tej.as/blog/2020-in-review/https://tej.as/blog/2020-in-review/A month-by-month look back at my 2020: the friends, family, and small moments that made a pandemic year worth being thankful for.Fri, 01 Jan 2021 17:15:40 GMThttps://tej.as/blog/5-things-i-love-about-my-website/https://tej.as/blog/5-things-i-love-about-my-website/I walk through five things I love about my website, including automatic dark mode, Next.js server rendering, whimsy, and GitHub as my backend.Mon, 20 Jan 2020 18:05:54 GMThttps://tej.as/blog/ai-evals-llm-judge/https://tej.as/blog/ai-evals-llm-judge/AI evals are fuzzy unit tests. My AI Engineer World's Fair workshop, written up: build an LLM judge, catch its biases and gate deploys on it.Tue, 06 Oct 2026 07:22:23 GMThttps://tej.as/blog/aleph-alpha-kolibri/https://tej.as/blog/aleph-alpha-kolibri/Kolibri is Aleph Alpha's open-weight German and English LLM: 78B parameters, 3.5B per token. How it works, what it's good and bad at, and when to use it.Sat, 03 Oct 2026 08:47:15 GMThttps://tej.as/blog/apple-watch-readiness-score-wrong/https://tej.as/blog/apple-watch-readiness-score-wrong/My Apple Watch told me to Go For It on my most run-down mornings. Why the Readiness score misses and the readiness app I built in 5 days.Thu, 08 Oct 2026 11:00:00 GMThttps://tej.as/blog/biggest-lessons-2024-honor-people-fear-failure/https://tej.as/blog/biggest-lessons-2024-honor-people-fear-failure/Dissecting honor, what it takes to overcome trauma, how to heal from the fear of failure and prioritize relationships.Sat, 28 Dec 2024 18:36:52 GMThttps://tej.as/blog/can-ai-feel-pain/https://tej.as/blog/can-ai-feel-pain/Nobody can prove AI feels pain, but 25 open models have a pain direction that rises when you insult them. What it shows and why they're still machines.Fri, 09 Oct 2026 10:09:44 GMThttps://tej.as/blog/can-you-run-muse-spark-open-locally/https://tej.as/blog/can-you-run-muse-spark-open-locally/Meta says Muse Spark Open runs on your desktop. It needs 493 GB of memory and my MacBook Pro has 16. The desktop is Mac Studios you can't buy yet.Fri, 16 Oct 2026 12:00:00 GMThttps://tej.as/blog/coding-nights-weekends-good-work-life-balance/https://tej.as/blog/coding-nights-weekends-good-work-life-balance/I love coding on nights and weekends because it's my favorite hobby. It only becomes a problem when it turns into a god or an expectation.Sun, 22 Dec 2024 19:27:38 GMThttps://tej.as/blog/companies-are-full-of-it/https://tej.as/blog/companies-are-full-of-it/My case against bar raiser interviews, Objectives and Key Results (OKRs), the Spotify model and agile, why AI makes it urgent and how I'd hire instead.Tue, 13 Oct 2026 13:00:00 GMThttps://tej.as/blog/goodbye-facebook/https://tej.as/blog/goodbye-facebook/Why I'm deleting Facebook, Instagram, and WhatsApp: FOMO, lost time, and engagement algorithms that radicalize people. I'm moving to Signal instead.Mon, 11 Jan 2021 14:09:01 GMThttps://tej.as/blog/health-fitness-devrel-hemophilia/https://tej.as/blog/health-fitness-devrel-hemophilia/A deeply personal post about my health journey and how it's affected my fitness, devrel work, and more.Sat, 03 Sep 2022 00:00:00 GMThttps://tej.as/blog/hello-world/https://tej.as/blog/hello-world/My first post here: a quick hello world I published to make sure the blog works. The real writing starts after this one.Mon, 13 Jan 2020 13:36:14 GMThttps://tej.as/blog/how-long-should-a-keynote-speaker-speak/https://tej.as/blog/how-long-should-a-keynote-speaker-speak/A keynote runs 20 to 45 minutes, most often 30. What the attention research really says, what conferences schedule, and how to use the slot you get.Mon, 14 Sep 2026 18:30:00 GMThttps://tej.as/blog/how-much-does-a-keynote-speaker-cost/https://tej.as/blog/how-much-does-a-keynote-speaker-cost/A keynote speaker costs $2,500 at the median in 2026 and $10,000 to $25,000 for an established author, plus travel. The benchmarks and what moves them.Thu, 01 Oct 2026 14:40:59 GMThttps://tej.as/blog/how-to-grow-professional-relationships-tjs-model/https://tej.as/blog/how-to-grow-professional-relationships-tjs-model/My TJS model maps professional relationships across seven states, from zero-sum competition to toxic enmeshment, and why collaboration is the peak.Thu, 28 Nov 2024 00:00:00 GMThttps://tej.as/blog/impact-pillars-web-engineering/https://tej.as/blog/impact-pillars-web-engineering/I break down the four pillars of impact for web engineers: emotional, social, creative, and technical, and how to grow each one over time.Thu, 10 Mar 2022 20:37:25 GMThttps://tej.as/blog/kolibri-vs-claude-german-llm-benchmark/https://tej.as/blog/kolibri-vs-claude-german-llm-benchmark/Aleph Alpha's Kolibri lost all 136 blind comparisons to Claude Sonnet 5.5 at German Bible deep dives, despite clean grammar and a leaner tokenizer.Mon, 05 Oct 2026 12:00:00 GMThttps://tej.as/blog/levels-of-agentic-coding/https://tej.as/blog/levels-of-agentic-coding/I've built with 1 agent, 8 agents in parallel worktrees and a software factory that ran for days on its own. My sweet spot is level 2 or 3. Here's why.Sat, 17 Oct 2026 12:00:00 GMThttps://tej.as/blog/local-llm-vs-cloud/https://tej.as/blog/local-llm-vs-cloud/I've run models on my phone, my laptop and rented GPUs. An $18,000 AI server wins on privacy and loses on price unless it's busy all day.Wed, 14 Oct 2026 13:37:23 GMThttps://tej.as/blog/note-app-ai-benchmark-apple-intelligence-sucks/https://tej.as/blog/note-app-ai-benchmark-apple-intelligence-sucks/Apple Intelligence refused my voice note, so I benchmarked 11 AI models on it. A cheap one beat the frontier and my phone's Qwen made things up.Wed, 08 Jul 2026 06:56:00 GMThttps://tej.as/blog/please-stop-the-slop/https://tej.as/blog/please-stop-the-slop/My verdict on AI slop: what it is, how to spot it, why not all AI is slop and a petition to keep the internet human.Sat, 10 Oct 2026 13:00:00 GMThttps://tej.as/blog/pressure-power-and-peace/https://tej.as/blog/pressure-power-and-peace/Acts 1:8 promises power when the Holy Spirit comes upon you. When I burned out, a pastor in Belgrade showed me what that power does to pressure.Sun, 18 Oct 2026 05:00:00 GMThttps://tej.as/blog/super-intelligence-isnt-superior/https://tej.as/blog/super-intelligence-isnt-superior/US agencies now call AI Super Intelligence (SI), yet its definition didn't change. What it beats people at, where it fails, and why people make idols.Sun, 04 Oct 2026 13:55:00 GMThttps://tej.as/blog/what-are-open-weights/https://tej.as/blog/what-are-open-weights/Open weights means you can download a model and run it yourself. What the GPT-4o petition is really asking, and why releasing the weights is the hard part.Wed, 07 Oct 2026 16:24:58 GMThttps://tej.as/blog/what-does-the-bible-say-about-ai/https://tej.as/blog/what-does-the-bible-say-about-ai/The Bible never mentions AI, but it says plenty about who we are, what we make and who we trust. An AI engineer who builds a Bible app on what that means.Sat, 26 Sep 2026 09:00:00 GMThttps://tej.as/blog/what-i-learned-from-getting-pushed-off-my-bicycle/https://tej.as/blog/what-i-learned-from-getting-pushed-off-my-bicycle/A blog post about things I learned after being randomly attacked on the streets of Berlin when a stranger pushed me off my bicycle.Wed, 15 Jan 2020 08:56:36 GMThttps://tej.as/blog/what-is-an-agent-harness/https://tej.as/blog/what-is-an-agent-harness/An agent harness is everything around an AI model that grounds it in reality: tools, context, guardrails, the loop and verification. How to build one.Mon, 14 Sep 2026 09:47:55 GMThttps://tej.as/blog/what-is-good-taste-in-software/https://tej.as/blog/what-is-good-taste-in-software/Good taste in software is a trainable skill: judging quality against external standards. 6 practice protocols, with the research under each one.Sun, 20 Sep 2026 10:00:00 GMThttps://tej.as/blog/what-is-react-fiber/https://tej.as/blog/what-is-react-fiber/React Fiber is how React has rendered since version 16: a tree of small units of work it can pause and resume. How it works, from the React source.Wed, 30 Sep 2026 08:30:00 GMThttps://tej.as/blog/what-is-webmcp/https://tej.as/blog/what-is-webmcp/WebMCP is a proposed web standard that lets a page give AI agents tools to call. How tej.as offers agents 4 of them, and what WebMCP is good for.Fri, 02 Oct 2026 07:50:41 GMThttps://tej.as/blog/why-ai-cant-replace-human-taste/https://tej.as/blog/why-ai-cant-replace-human-taste/AI can't replace human creativity or taste: we crave novelty and a model makes what's most common. My answer to a question after my talk in Prague.Mon, 12 Oct 2026 15:29:17 GMThttps://tej.as/blog/why-i-do-not-prefer-speaking-at-remote-conferences/https://tej.as/blog/why-i-do-not-prefer-speaking-at-remote-conferences/Why I'd rather not speak at virtual conferences during COVID-19: the hallway conversations are the point, and video calls lose that connection.Mon, 16 Mar 2020 16:36:28 GMThttps://tej.as/blog/why-i-think-remote-work-is-incredible/https://tej.as/blog/why-i-think-remote-work-is-incredible/Two months into my first fully remote job, I compare it with office life: deeper focus, better health, and the sleep rhythm trap I had to fix.Mon, 27 Jan 2020 13:40:59 GMT