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Show HN: Red Grid Link – peer-to-peer team tracking over Bluetooth, no servers

2026-03-20 @ 22:25:51Points: 21Comments: 12

Red Grid Link does that. Start a session, and anyone nearby running the app shows up on your offline map. When they walk out of range their marker stays as a "ghost" that slowly fades.

The hard part was making sync reliable over BLE. The connections drop all the time. Someone turns a corner, walks behind a vehicle, whatever. I built a CRDT sync layer (LWW Register + G-Counter) so there's never merge conflicts. Each update is just under 200 bytes (from what I have tested so far). When a user/teammate disappears the app does exponential backoff from 2 to 30 seconds before giving up and marking them as a ghost.

Everything is encrypted (AES-256-GCM, ECDH P-256 key exchange per peer pair). Sessions can require a PIN or QR code to join. It also offers offline topo maps with MGRS grid coordinates, same system as in my other app, Red Grid MGRS.

The app is free, and I'm looking for some honest feedback from other real-world users. Let me know if you have any questions!

Ghostling

2026-03-20 @ 22:11:37Points: 98Comments: 10

Show HN: We built a terminal-only Bluesky / AT Proto client written in Fortran

2026-03-20 @ 22:06:51Points: 43Comments: 30

Yes, that Fortran.

We rewrote our Rust WASM Parser in TypeScript – and it got 3x Faster

2026-03-20 @ 21:48:06Points: 109Comments: 59

Discontinuation and reinitiation of dual-labeled GLP-1 receptor agonists

2026-03-20 @ 21:42:16Points: 56Comments: 80

Show HN: Baltic shadow fleet tracker – live AIS, cable proximity alerts

2026-03-20 @ 21:04:11Points: 31Comments: 6

OpenCode – The open source AI coding agent

2026-03-20 @ 21:03:52Points: 456Comments: 206

A Japanese Glossary of Chopsticks Faux Pas

2026-03-20 @ 20:54:57Points: 120Comments: 107

NumKong: 2'000 Mixed Precision Kernels for All

2026-03-20 @ 19:29:39Points: 33Comments: 0

Our commitment to Windows quality

2026-03-20 @ 19:16:13Points: 414Comments: 749

Attention Residuals

2026-03-20 @ 18:23:41Points: 127Comments: 20

Show HN: I made an email app inspired by Arc browser

2026-03-20 @ 18:06:20Points: 49Comments: 27

The Arc browser brought joy and taste to browsing the web. Cursor created a new UX with agents ready to work for you in a handy right panel.

I use these three tools every day. Since Arc was acquired by Atlassian, I’ve been wondering: what if I built a new interface that applied Arc’s UX to email rather than browser tabs, while making AI agents easily available to help manage emails, events, and files?

I built a frontend PoC to showcase the idea.

Try it: https://demo.define.app

I’m not sure about it though... Is it worth continuing to explore this idea?

Launch HN: Sitefire (YC W26) – Automating actions to improve AI visibility

2026-03-20 @ 17:05:38Points: 33Comments: 22

https://sitefire.ai). Our platform makes it easy for brands to improve their visibility in AI search.

We’ve been working together for years and have backgrounds in RL/optimization at Stanford and software engineering. We came to this idea after speaking with marketing teams who were seeing declining traffic due to Google’s AI Overviews and didn’t know what to do.

This space can feel esoteric. Many case studies, few actual studies. Constant battle against myths (e.g. you need a llms.txt vs. you don't need a llms.txt) and "GEO hacks". We try to be more data-driven. And we try to be more bold and build a system that not only monitors, but actually improves traffic from AI search.

While Google performs a single search, AI search engines expand the user prompt into 3-10 fan-out queries. The sourced pages are ranked using a classified algorithm similar to Reciprocal Rank Fusion (RFF). Finally, the LLMs skim the pages and decide what snippets to cite. Our goal is making sure brands have the right content that makes it through this funnel.

Here is how sitefire works:

- The user defines a set of prompts they want to monitor. These are synthetic prompts - we generate them based on SEO keywords and their monthly search volume.

- We submit these prompts to ChatGPT, Gemini, Google AI Mode, etc. on a daily basis and capture the answers. We extract fan-out queries, sourced pages, citations, and brand mentions.

- For each topic, our agents analyze which web pages are sourced and cited the most, and why. They also consider similar pages that you already have.

- Based on the diagnosis, our content agents draft improvements or create new pages, and push them directly to the client’s CMS.

- We integrate with the client’s network logs and Google Analytics to monitor the increase in AI bot requests and human referrals to their page.

This system is continuously updated, so it always shows which content works, and how to adapt the existing sitemap. For one client that used sitefire to optimize their blog, the AI-optimized articles increased their AI bot requests from ~200/day to ~570/day within ten days.

A risk we recognize is that AI-generated content is filling brands’ websites with slop. Whilst it’s still early days and we don’t claim to have figured everything out yet, our intention is to mitigate this by focusing the content on specific, unique information: real product capabilities, real pricing, honest comparisons. The clients still review every page before it goes live, so they can ensure the content is true to their brand.

Some clients use our platform themselves. For others we act more like an agency, automating steps as we go. The goal is for sitefire to run mostly on its own, with clients approving changes via Slack, Claude or their CMS.

Here's a video demo: https://screen.studio/share/fw7VQQak

If you'd like to try what we've built so far, sign up at https://sitefire.ai.

Meme Buildings

2026-03-20 @ 15:55:40Points: 21Comments: 2

Super Micro Shares Plunge 25% After Co-Founder Charged in $2.5B Smuggling Plot

2026-03-20 @ 14:48:09Points: 325Comments: 135

The Social Smolnet

2026-03-20 @ 13:02:19Points: 110Comments: 13

France's aircraft carrier located in real time by Le Monde through fitness app

2026-03-20 @ 13:01:56Points: 475Comments: 397

Entso-E final report on Iberian 2025 blackout

2026-03-20 @ 11:03:27Points: 176Comments: 74

Delve – Fake Compliance as a Service

2026-03-19 @ 19:08:02Points: 555Comments: 195

An FAQ on Reinforcement Learning Environments

2026-03-19 @ 12:24:46Points: 22Comments: 4

Work_mem: It's a Trap

2026-03-18 @ 20:52:30Points: 32Comments: 2

Parallel Perl – Autoparallelizing interpreter with JIT

2026-03-18 @ 11:59:05Points: 100Comments: 37

The worst volume control UI in the world (2017)

2026-03-18 @ 10:22:38Points: 67Comments: 30

The Los Angeles Aqueduct Is Wild

2026-03-17 @ 18:43:53Points: 297Comments: 164

I love my dumb watches

2026-03-17 @ 15:45:17Points: 64Comments: 65

VisiCalc Reconstructed

2026-03-17 @ 10:39:55Points: 166Comments: 69

Flash-KMeans: Fast and Memory-Efficient Exact K-Means

2026-03-17 @ 05:38:26Points: 171Comments: 14

Video Encoding and Decoding with Vulkan Compute Shaders in FFmpeg

2026-03-17 @ 01:02:41Points: 151Comments: 54

Show HN: An open-source safety net for home hemodialysis

2026-03-17 @ 00:48:15Points: 41Comments: 6

FSF statement on copyright infringement lawsuit Bartz v. Anthropic

2026-03-16 @ 19:49:20Points: 256Comments: 127

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