Guides for sealing things away

These guides cover the practical side of writing to your future self: what to put in a letter, how to run a prediction game with friends, ideas for adult time capsules, how to score guesses fairly, and how time-lock encryption keeps a digital capsule closed.

Coming soon to iPhone

What is in the guides?

Each guide stands on its own, and none of them needs the app. If you want a tool for the job, Sealday does the sealing, the waiting and the opening.

Where should I start?

Writing to yourself is the easiest entry. Begin with how to write a letter to your future self, then try a birthday letter or a voice message if writing feels stiff.

If you want something for a group, the New Year guides show how to run a prediction game for friends, and the ones on scoring predictions show how to grade it fairly.

Which guide fits which occasion?

Personal: letters, a ten-year capsule, year-in-review questions.
Family and milestones: baby, family, graduation, wedding and couples capsules.
Parties: New Year's Eve games and predictions for friends.
Thinking tools: better predictions, hindsight bias, resolutions versus predictions.
How it works: time-lock encryption and keeping digital memories safe.

Do I need the app for any of this?

No. Every guide works with paper, a shared document or any notes app. Sealday adds a lock that holds until the date, a way to grade guesses on open day and a backup file. The guides say where a feature helps and link to the matching page.

Baby Time Capsule IdeasWhat to put in, which birthday to open on and how to keep a digital capsule safe for years.Birthday Letter to YourselfA yearly ritual with prompts, a template and ideas for what to do on the day you open it.Couples Time Capsule IdeasTen questions, shared guesses and the right dates for an anniversary or a big move.Email to Your Future Self vs a Sealed Time CapsuleWhere scheduled email works, where it breaks, and when a sealed capsule is the better tool.Family Time Capsule Ideas for Holidays and ReunionsIdeas by age, questions for the whole table and how to seal and open it next holiday.Graduation Time Capsule Ideas for Classes and FriendsQuestions, prompts and a reunion plan for a class, a friend group or a solo graduate.How Long Should a Time Capsule Stay Sealed? By PurposeA guide to choosing 1, 5, 10 or 20 years, with the risks that grow as you wait.How Time-Lock Encryption WorksEncrypting to a future moment with the drand beacon, in plain language.How to Get Better at Making Predictions in Daily LifeSix habits for better predictions, a simple scoring formula and a one-year practice plan.How to Keep Digital Memories Safe for 10 Years or MoreThe 3-2-1 habit, formats that last, an annual check and a vault file routine for capsules.How to Make a Digital Time Capsule That Stays ClosedFour ways to build one, how to compare them and a checklist for contents and backups.How to Score Your PredictionsWrite checkable guesses, tag your confidence, seal, then grade with three marks.Letter to Your Future SelfWhat to write, 12 prompts, a template and how to keep the letter safe.New Year Predictions for FriendsRules, 15 questions and scoring for a New Year prediction game with friends.New Year Resolutions vs PredictionsHow resolutions and predictions differ, and a one-evening method that uses both.New Year's Eve Games for Adults That Need No PropsSeven phone-light games for a flat party, with timing, group size and how to run the prediction game.Predictions for 2027Twenty starter predictions for 2027, rules for making them checkable and how to seal and grade them.Ten-Year Time CapsuleWhat to write for a stranger who is you, what will change, and a yearly checklist.Then and Now Photo IdeasTwenty subjects, framing tips and how Sealday pairs a then photo with a now photo on open day.Time Capsule Ideas for AdultsTwenty ideas, how long to wait and how to store a digital time capsule.Time Capsule QuestionsForty questions in four groups, with tips on how many to answer and how to open them.Voice Message to Your Future SelfA script, prompts and practical tips for recording, locking and keeping a voice note for later.Wedding Time Capsule Ideas Guests Will Actually Fill InWhat to collect, when to open it and how to keep guest entries private until the anniversary.What Is Hindsight Bias? Examples and How to Beat ItA definition, everyday examples, the classic study and a way to counter it with a sealed record.Year in Review QuestionsForty questions in four groups, plus a method for answering and what to do with the answers.

Frequently asked questions

How long should I wait before opening a capsule?

One year suits predictions and a New Year game. Five to ten years suits letters and family capsules. The guide on how long a capsule should stay sealed weighs the risks that grow with time.

Are these guides only about the app?

No. They cover writing, ideas, scoring and storage on their own. The app is mentioned where it has a matching feature.

What is the difference between a letter and a prediction?

A letter records how things feel now. A prediction is a checkable guess about the future that you can mark right or wrong on open day.

Is a digital time capsule safe?

It is as safe as its backup. Keep a second copy, check it once a year and choose formats that open on future devices. The guide on keeping digital memories safe has a checklist.

Keep exploring

Sealday FeaturesThe time lock, predictions, letters, Tables, friend capsules and backups in Sealday.How the Sealday Time Lock WorksAES-256 on the device plus a drand timelock: the key does not exist until the open date.Letter to Your Future SelfWhat to write, 12 prompts, a template and how to keep the letter safe.How to Make a Digital Time Capsule That Stays ClosedFour ways to build one, how to compare them and a checklist for contents and backups.