Hackernews posts about W21

W21 is a year class in Y Combinator's (YC) accelerator program, indicating that these are startups that were part of the Winter 2021 batch.

1. Show HN: Cost.dev (YC W21) – making agents cost-aware and cheaper to call (cost.dev)
   48 points by akh 15 days ago | 29 comments
2. Launch HN: Adam (YC W25) – Open-Source AI CAD (github.com)
   210 points by zachdive 2 days ago | 97 comments
3. How to get into Y Combinator: notes from a W23 alum (github.com)
   3 points by iCarossio 18 days ago | discuss
4. Open (YC W24): we'll refund every dollar, up to $2M, if our AI agent disappoints (www.open.cx)
   2 points by gharbat 4 days ago | 1 comments
5. The State of Ship Quality: We Audited Every YC W26 Website (overlayqa.com)
   2 points by emvied 9 days ago | 1 comments
6. Show HN: Talos – Open-source WASM interpreter for Lean (github.com)
   89 points by mfornet 1 day ago | 22 comments
7. Show HN: Integuru – Integrate with platforms via the source code (www.integuru.com)
   7 points by alanloo 21 days ago | discuss
8. Show HN: Open-Sourced Approxima, Our Agentic QA Tool to Catch Breakages Faster (github.com)
   2 points by Intragalactic 6 days ago | discuss
9. Colossal Squid Are Everywhere. We've Been Looking Wrong [video] (www.youtube.com)
   4 points by mpweiher 4 days ago | discuss
10. The Fix for AI's Spending Problem Is Not Good for OpenAI and Anthropic [video] (www.youtube.com)
    3 points by mgh2 14 days ago | discuss
11. Louis Rossmann: Here's Why You Won't See My Videos in Recommended in the Future (www.youtube.com)
    3 points by Cider9986 22 days ago | discuss
12. Interest Rate May Explain Consumer Sentiment Anomaly (www.nber.org)
    3 points by efavdb 25 days ago | discuss
13. A framework for systematically addressing undefined behavior in the C++ Standard [pdf] (www.open-std.org)
    1 points by linkdd about 2 hours ago | discuss
14. OS Written in Embedded Swift (github.com)
    1 points by w10-1 about 2 hours ago | 1 comments
15. DaVinci Resolve 21 (www.blackmagicdesign.com)
    545 points by pentagrama 16 days ago | 278 comments
16. DynIP – Dynamic DNS with RFC 2136, IPv6, DNSSEC, and BYOD (dynip.dev)
    341 points by dynip 25 days ago | 128 comments
17. 21 years and counting of 'eight fallacies of distributed computing' (2025) (blog.apnic.net)
    144 points by teleforce 5 days ago | 56 comments
18. Show HN: NBSDgames – 21 new, improved, original text games for Unix, DOS, Plan9 (github.com)
    13 points by abakh 9 days ago | 1 comments
19. Ask HN: What are you working on? (May 21)
    10 points by Armonsrer 29 days ago | 49 comments
20. Show HN: Taliesin – bit-exact KV-cache restore, 21x faster, cross-GPU verified (medium.com)
    10 points by Wetime 15 days ago | 7 comments
21. FOSS Weekly #26.21: Microsoft's Distro, Bitwarden Drama, and More (itsfoss.com)
    5 points by abdelhousni 29 days ago | 3 comments
22. NIS2 Email Security: Mapping Article 21 Controls to DMARC, MTA-STS, and Dane (dmarcguard.io)
    4 points by meysamazad 18 days ago | discuss
23. Cohere Open-Sources Command A+, a 218B Moe Model That Runs on Two H100s (firethering.com)
    4 points by steveharing1 27 days ago | discuss
24. Starship launch today, May 21, 2026 (www.space.com)
    4 points by valgin2150 29 days ago | discuss
25. AMD Threadripper CPUs Unlock Up to 215% Faster HandBrake Transcoding (www.amd.com)
    3 points by speckx 1 day ago | discuss
26. Show HN: GoldenMatch – 100M-row dedupe on Ray in 213s, no Spark, Arrow-native (github.com)
    3 points by benzsevern 15 days ago | discuss
27. Show HN: I indexed 21,509 Shopify App Store listings (www.appstorepulse.com)
    3 points by matdesousa 17 days ago | discuss
28. The Story Behind Paul and Pascale’s $10,000 Grants to 21 Woodworkers (Part 1) (christopherschwarz.substack.com)
    3 points by crescit_eundo 18 days ago | discuss
29. 21 days, $5K, 7 AI agents: how a non-programmer built a talent marketplace (www.bearhugrecruiting.com)
    3 points by kraigward 21 days ago | discuss
30. Simplicity always wins:SOTA on swe-pro,tb2,-verif on 21 models with simple-agent (github.com)
    2 points by gaurav71531 about 2 hours ago | 1 comments