Show HN: Flashpaper – Self-destructing secret sharing with no database

Show HN: Flashpaper – Self-destructing secret sharing with no database(flashpaper.app)

21 points by minpym 3 hours ago | 4 comments

Hi everyone! This is my first HN and I’m very new to the scene. My name is Min from Bangkok.

At first, I just want to create a dead man's switch for personal use and for fun. then, I think about information that self destruct like a spy movie. after that, I try to come up with the better version of Privnote or Bitwarden with self-destruct and some kind of censoring or blocking download ability. Somehow, end up with this product. :O

Flashpaper is for sending any information that would be burned after reading (with counting down timer like Mission Impossible movie ! or after 24 hrs max if not opened) Encryption happens in browser and because the key stays after # in the link; server never sees the key (Zero-knowledge for web use) and— because I’m a newbie. I don’t want to connect to database because I don’t have the money and I want things light and simple. So, that’s why Flashpaper keeps things in RAM-only, no database.

For AI Agent side, Flashpaper provides a REST API and an MCP server so agents can create secret links easily in dead-drop style that can be claimed only once. The second claim would get a 404 which means someone already took it. However, for the agent API flow, the server sees the plaintext for a moment before encrypting, so this flow is not zero-knowledge like the web flow.

Overall, I think it work quite well for web use, but for agent API use, I am not sure this is enough security. All the limitations are listed in SECURITY.md. Some feedback would be appreciated. I make it open source with MIT license, with honorware policy for Enterprise use, like self-hosted docker.

Here is my repo https://github.com/mmmpym/flashpaper and you can try it here https://flashpaper.app

Again ! Please feel free to tell me what I missed.

Min

Ardon 35 minutes ago |

This is very cool. I can't comment on the encryption, but I did want to mention that your page design is pretty bad, which is a shame for something so useful.

It looks AI generated, you can probably paste this into your LLM of choice to improve it.

It has pretty subtle information hierarchy. All the text sizes except for the main heading are withing 15% size of each other. More differentiation here would be the lowest hanging fruit, I think. I'd also say all the text needs to increase in size in general. It's pretty low contrast as well, made worse by the small font size. And some things, like button highlights, are too high-contrast. They pull too strongly away from the rest of the text and flow. You also have a lot of buttons, some of them are even just to pre-fill demo text. I'd cut it way down.

I think the goal should be that the critical path to making a 'burn link' is at the very top of the information hierarchy. Big heading "Your Secret", with very well signposted text box. Big heading "Link Expiration" with a big range slider (with number input.)

(Sliders have the advantage of structurally communicating what you're doing. You fill up the available slider to add more time, you shrink it to have less time.)

The overall idea is that the eye naturally snaps to the next step when the previous one is done with zero effort. Really blast the information and steps into people's brains.

I hope Flashpaper takes off!

minpym 20 minutes ago | |

Thank you so much for constructive feedback!

You caught me. The design is AI-generated, I built the whole app with AI tools.

Really apprecaite the pointers; I agree with what u said, and will try re-read it again tomorrow (it 1.30 am here haha) and adjust the design.

Again. Thanks a lot for your support and kind words!

ronak_parmar 3 hours ago |

some great tech, what problem do you encounter that led you to develop it?

minpym 3 hours ago | |

tbh, mostly just for fun. but also a bit issue from when I type API key in Claude and it's always remind me to delete or regen API keys. i think this might solve that.