Hi Product Hunt! I'm DONGGYU LEE, the developer of Letterveil.

What would you tell yourself at the start of a new chapter? And what would you say back after living through it?

Letterveil is a time capsule for that conversation. You can write to yourself seven days from now, revisit a decision in 30 days, or leave a letter to open at the end of the year.

Here's the flow:

1. Write a letter with up to three photos. Prompts can help you put a choice, a worry, or an expectation into words.

2. Choose an opening date and seal it.

3. When the day arrives, open it and add a reflection.

4. Write a linked reply, then read your earlier words and your response side by side.

The reply is the part I want to highlight: the conversation can continue as your perspective changes.

A few practical details:

- Available on iOS and Android, with no Letterveil account required.

- Letters and photos are encrypted on your device. There's no automatic cloud sync; use the manual encrypted backup when moving devices.

- App lock, a hidden archive, and PDF/Markdown export are included.

- The free version includes 10 lifetime seals. An optional one-time lifetime upgrade removes the sealing limit. No subscription.

The short English video shows the flow with example letters; the gallery shows the app's English interface.

For a first letter, would you choose seven days, 30 days, or the end of the year? I'd also love to hear whether the reflection-and-reply flow feels clear, and what would make you want to return when a letter opens.

Thanks for taking a look!