Interstitial
For ADHD brains

A journal that walks through the day with you.

You write what you're doing as you do it. The app quietly notices when "do laundry" is hiding three concrete steps — and helps you find the first one.

Try it free for 14 days → See how it works
No credit card. No onboarding quiz. Works offline from day one.
E2E
Encrypted
0
Trackers
3
Platforms
$2.99
/ month
Friday, April 10
02:47 elapsed
9:14
made coffee, opened laptop
9:31
"do laundry"
gather clothes from floor
put in washer
set 5 min timer
10:02
answered two emails
what are you doing right now?
On-device
Zero-knowledge
No streaks
The premise

Not a planner. Not a habit tracker. A present-tense journal.

Planners ask what you'll do tomorrow. Habit trackers ask whether you did the thing today. Both require a version of you that can see forward or backward clearly. ADHD time is mostly the current minute.

So Interstitial only asks one question: what are you doing right now? That's the whole interface. The app listens, notices when an entry is vague, and offers to break it into the smallest physical first step.

Over weeks, it quietly builds a picture — when you focus best, what drains you, which kinds of tasks you finish and which you don't. No leaderboards. No streaks. Returning after a three-week gap feels identical to the first session.

Four quiet mechanics

Small ideas, applied with discipline.

01 · VAGUENESS DETECTION

An entry like "do laundry" isn't a task. It's three.

A small on-device classifier watches what you write. Concrete entries ("answered Maya's email") land silently. Vague entries ("work on deck") get a gentle, dismissable prompt: what's the very first physical thing?

  • Runs entirely on-device. No content leaves your phone.
  • Never interrupts. Prompt is always skippable.
  • Up to five sub-steps per entry — never more.
Example
"work on deck"
↓
What's the very first physical thing?
open the Keynote file
rewrite the title slide
move slide 4 before slide 2
02 · THE STUCK BUTTON

For the minutes you can't describe what you're doing — because you can't start.

One button, always within reach. Tap it and the screen breathes with you: a slow spiral, a single question, no timer, no guilt. When you're ready, it offers the smallest possible first action.

  • No countdown. No pressure. Leave anytime.
  • Tracks nothing. Not even that you opened it.
  • The app never mentions it in patterns.
Still here.
Whenever you're ready.
03 · WEEKLY OBSERVATIONS

Not dashboards. Sentences.

Once a week, Interstitial reads back what it saw. No charts to decode, no percentages to feel bad about — just short, dry observations written like a friend who was paying attention.

  • Generated on-device from local aggregates.
  • Never compared to other users. No "average."
  • Dismissable. Turn it off entirely in Settings.
OBSERVATION · WEEK 14

You wrote fourteen entries on Tuesday and three on Thursday. The Thursday entries were mostly between 2pm and 4pm.

OBSERVATION · WEEK 14

Vague entries tagged "deep work" were completed more often on mornings you logged "slept well."

04 · ZERO-KNOWLEDGE

We literally can't read your journal.

Your password derives a key on your device via Argon2id. Every entry is encrypted with XChaCha20-Poly1305 before it leaves. The server stores random bytes — not a word of your journal touches a database we can read.

  • No third-party analytics SDKs. Ever.
  • Export everything as decrypted JSON anytime.
  • Delete your account with one confirmation. All blobs gone in 24h.
// what the server sees
const blob = {
  id: "ent_9f2a...",
  nonce: "a3f1...e9",
  ciphertext: "7b4c...2f",
  tag: "9e1d...44",
  created_at: 1744320840
}
Design principles

Restraint over features.

Every decision in the product passes through these six filters. If it fails any of them, it doesn't ship.

01

Present-moment focus.

The app exists to capture what is happening right now — not to plan the future, not to audit the past. Every screen asks some version of the same question: what are you doing?

02

Concrete over abstract.

Vague intentions become physical first actions. The system actively resists fuzzy language.

03

No shame.

No streaks, scores, or guilt prompts. Ever.

04

Quiet tone.

Dry, warm, present. Never cheerful. Never congratulatory.

05

Privacy as a product feature.

Encryption is not a marketing bullet — it's the architecture. Your keys derive on-device. Our servers see opaque blobs.

06

Offline first.

Airplanes, subways, basements. It all works.

Zero-knowledge architecture

Cryptography you could audit on a whiteboard.

No rolling our own crypto. Interstitial uses libsodium primitives that are public, peer-reviewed, and the same ones that back Signal, WireGuard, and Age.

When you sign up, your device generates a random 256-bit master key. Your password wraps it via Argon2id. We store the wrapped key and random bytes. We cannot unwrap anything — not with a warrant, not with a leak.

  • Entry cipher XChaCha20-Poly1305
  • Key derivation Argon2id · 64 MB
  • Key storage iOS Keychain / Android Keystore
  • Web trust root non-extractable CryptoKey
  • Transport TLS 1.3 · HSTS · pinned
entryEncryption.ts
// every entry, before it leaves
function encryptEntry(plaintext, masterKey) {
  const nonce = sodium.randombytes_buf(24);
  const ciphertext =
    sodium.crypto_aead_xchacha20poly1305(
      plaintext,
      aad,
      nonce,
      masterKey
    );
  return { nonce, ciphertext };
}
● Audited primitives
● No rolling our own
Pricing

One price. One product. No surprise tiers.

Start with 14 days free. No credit card required to try it.

Interstitial
$2.99/ mo
billed monthly
or $12/year — save 67%
  • Unlimited entries, iOS · Android · web
  • On-device vagueness detection
  • Weekly pattern observations
  • End-to-end encrypted sync across devices
  • Full decrypted JSON export, anytime
  • No ads. No tracking. No third-party SDKs.
Start 14-day free trial →
Lapsed subscriptions

We never hold your data hostage.

Cancel anytime. You keep read-only access to every entry you wrote, and can export everything even after the subscription ends.

Frequently asked.

Still curious? support@interstitial.app
Will I lose my data if I stop paying? +
No. After your subscription ends, you keep read-only access to every entry you've written and can export everything anytime. The product never holds user data hostage.
What does "zero-knowledge" actually mean? +
Your password unlocks a key on your device. That key encrypts every entry before it leaves. We only ever see random bytes — not with a warrant, not with a leak, not even accidentally.
Does it work offline? +
Fully. Entries write to a local queue and sync when connectivity returns. Even vagueness detection runs on-device.
What if I forget my password? +
Because your password is also your encryption key, we cannot reset it for you — that's the tradeoff for real zero-knowledge. If you reset it, entries from before the reset become unreadable. Back up your password.
Is there an Apple Watch app? +
Not yet — it's on the v1.1 roadmap. For now, Interstitial runs on iOS, Android, and web with the same account.
How is this different from a bullet journal app? +
Bullet journals expect you to plan. Interstitial only asks what you're doing right now. That single change matters a lot to ADHD brains.

Try it for the next fourteen days.

If it doesn't fit, walk away. Your entries are yours to keep and export.

Start free trial → Read the premise again