Discover a user's contacts without ever knowing their contacts

In plain words

This is a privacy-preserving contact discovery server that identifies which of a user's contacts are registered on a service without exposing the contact list itself. Developed as an open-source project, it allows developers to implement contact discovery functionality while maintaining user privacy. The tool is hosted on GitHub for collaborative development and contributions.

written from the facts on this page · September 2026

• AF
  A free, privacy preserving, archive of public Discord servers2025 · searchcord.io · ▲70

  Hey HN! I have been working on this project for a while, and I think this solves a problem that a lot of people here have: not being able to easily search Discord servers. Currently, I only scrape servers that are marked as "discoverable" on Discord. However, if there's enough interest in the project, I'm open to adding specific servers by request. I'm primarily focused on informational servers rather than casual hangout spaces, such as open source projects, Minecraft mods, and support communities for tools, services, or platforms (for example, hosting providers). I have placed restrictions…

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  FellowGuard Contact Tracing2020 · fellowai.com · ▲13

  Precise Ultrawideband Contact Tracing & Occupancy Control

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  Secret Contact2025 · secret-contact.com · ▲7

  Secure and anonymous communication

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  An old school forum on an open protocol – your identity is a keypair23d ago · nostr-proto.org · ▲17

  This is a community forum for people who use, build, and run things on Nostr. Whether you are taking your first steps with keys and zaps, ship relays and clien…

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  Touchless PII Hasher2020 · app.narrative.io · ▲7

  Quickly and securely pseudonymize email addresses for free

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  Pcaller - Private Call Dialer2025 · apps.apple.com · ▲13

  Anonymous Number, Hidden ID

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  /dev/null▲490

  a social network for devs

  Dev tools · 4d ago · dev-null.sh

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  Whiteboard (YC W26) – an open-source IDE for thoughtful software design▲423

  open-source IDE for thoughtful software design. Contribute to devdotfast/whiteboard development by creating an account on GitHub.

  Dev tools · 28d ago · github.com

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  Reladraw – A diagram language where you decide where to place things▲411

  Contribute to reladraw/reladraw development by creating an account on GitHub.

  Dev tools · 26d ago · github.com

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  OpenBot▲362

  Grok Bot alternative: free, local, open-source, multiplayer

  Dev tools · 24d ago · openbot.run

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  Run full iOS 16.5 firmware on Android Devices▲349

  Contribute to oosexgang/hackios-xnu-kernel development by creating an account on GitHub.

  Dev tools · 13h ago · github.com

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  Talanoa▲346

  Hi HN, I’m a fullstack developer, and honestly, I’ve lost count of how many side projects I’ve worked on over the years. But one idea kept coming back to me: a different kind of email client. It first came to me in 2014: “What if we could handle emails more like conversations?” Every year, I’d revisit this concept in my “Build Notes.” Ten years later, no one had built exactly what I had in mind — so I finally decided to do it myself. That’s how Talanoa was born. I wanted something focused on people, not timelines. I was tired of marking messages as unread just to remember to reply later, or…

  Dev tools · 21d ago · talanoa.email

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  Brain.fm▲957

  Music for the brain to improve focus, meditation & sleep

  AI · 2015 · brain.fm

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  Something pointless I made▲747

  Life & fun · 2015 · dn.ht

• PA
  Parinfer – a simpler way to write Lisp▲674

  Parinfer - simpler Lisp editing

  Life & fun · 2015 · shaunlebron.github.io

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  Motion AI▲634

  Easily build chatbots to do anything, on any platform!

  AI · 2015 · motion.ai

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  f.lux for iOS▲596

  Auto adjust your iOS display based on the time of day

  Dev tools · 2015 · justgetflux.com

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  Fieldbook▲592

  Create a database, as easily as a spreadsheet

  Dev tools · 2015 · fieldbook.com