One File · Powerful productivity tracker
Every parameter.
Every water change.
An aquarium log in one HTML file. Tanks, parameter tests (pH / NH₃ / NO₂ / NO₃ / GH / KH / TDS / salinity), water changes, livestock — with anomaly detection that flags crashes before the fish do.
One payment · Yours forever · 14-day refund
- Works fully offline
- Installs as an app (PWA)
- No account, ever
- Yours, forever
Loads once, never needs the internet again. On a plane, in a basement, in a foreign hotel.
Every entry, every chart — stored locally. We never see it. We can't.
No subscription. No upgrades. No re-up next year. One file, yours.
Why log
Why fishkeepers end up with logs.
Tanks crash slowly; the trend lines reveal it before the fish do.
Parameter banner flags overdue + spikes.
Ammonia > 0.25 ppm, nitrite > 0.25 ppm, nitrate > 40 ppm — surfaced immediately. Test cadence too — 14+ days since last test gets flagged.
Crashes show up as anomalies.
On the trend line, before the fish tell you. Catch them in the dashboard, water-change in the morning, no losses.
Multi-tank, multi-type from day one.
Freshwater planted, reef, shrimp nano, brackish — all first-class types with their own parameter sets.
Livestock log is traceability.
Where you got the cardinal tetras, when added, count over time. Useful when troubleshooting deaths.
planted · nano shrimp · reef
across 6 months
no recurring fee, ever
log at the tank, no wifi
Inside the file
Eight things you'll use every day. Plus a dozen more.
One file. One dashboard. Every feature you'd expect from a "real" app — without the cloud, the cookies, or the £8/month.
Quick add
Log a parameter test from the home screen — three taps and back to your day.
Live insight banner
The single number that matters today, computed in real time from your entries.
Streak calendar
Daily streak across the last weeks. Showing up becomes the default.
Tier progression
Lifetime totals roll into satisfying tier badges as you log.
Water-change cadence
Rolling window with delta vs. the prior period. Spot the drift early.
Searchable, sortable list
Every entry findable in seconds — search across notes, sort by anything.
Photo per entry
Optional photo field stored locally as base64 — never uploaded.
PNG share cards
One-tap share card of your stats, ready for Instagram or a group chat.
Offline, always
Loads once, runs forever without a network connection.
Installs as a PWA
Add to home screen — opens like any native app.
CSV in / CSV out
Bring your old data in. Take everything with you. No lock-in.
No account, ever
No email, no signup, no analytics, no third-party tracking.
Yours forever
If we vanish tomorrow, your tracker keeps working — local file, no server.
Light + dark
Auto-follows the system. Or pick one and stick with it.
Today
Today, at a glance.
The home screen pulls together what just happened and what's coming up — clean enough to actually look at every morning.
- Live insight banner — your unique angle, computed from your entries
- Four-tile stat grid surfacing the numbers that matter today
- Streak calendar showing the last weeks at a glance
- Quick-add button — log without leaving the home screen
- Recent entries on the dashboard so the last log is one tap away
Tanks
Every tank, in one place.
Tank name, type, volume (l), set up on per row. Sortable, searchable, groupable.
- Search across tank name, filtration, lighting
- Sorted by tank name (A→Z)
- 10 fields per entry — the right amount of detail
Parameters
Every parameter test, in one place.
Date, tank, ph, ammonia (nh₃) per row. Sortable, searchable, groupable.
- Search across notes
- Sorted by date (newest first)
- 13 fields per entry — the right amount of detail
Water changes
Every water change, in one place.
Date, tank, percent changed, litres per row. Sortable, searchable, groupable.
- Search across notes
- Sorted by date (newest first)
- 7 fields per entry — the right amount of detail
How it's different
What you give up vs. aquarium apps. Smart-tank integration.
Compared with subscription aquarium apps.
- Pricing modelPay once · $8.99£8 – £15 / month, forever
- Account requiredNoYes
- Anomaly flaggingYesLimited
- Multi-tank freeYesOften paywalled
- Smart-controller integrationNoYes
- Data stays on your deviceYesNo
- Marketplace feesNoYes
The promise
Your tank is your business.
Not a fishkeeping marketplace's.
Offline, always
Open it once, never need the internet again. The file holds the whole app.
Local-first storage
Every entry stored in your browser, on your device. No server sync. No leaks. Nothing to breach.
One payment, forever
No subscription, no upgrade tier, no nag. If we shut down OneFileClub tomorrow, your file keeps working.
Data does not sync automatically between phone and desktop
This is a local-first app — everything stays on the device you logged it on. To use it on both phone and desktop, use the built-in JSON or CSV export on one device and import on the other when you want to keep them in step.
Every view, light and dark.
A look at every screen across both themes — your tracker, populated.
Questions
Real answers, no fine print.
Does it integrate with API / Salifert kits?+
No — that's a hardware integration. Read the colour, type the number; the act of writing makes the trend line reflective.
Can I share with my LFS for diagnostics?+
Yes. Export to CSV; the parameter rows are clean enough for a fishkeeper to read at a glance.
Where is my data stored?+
Locally, in your browser, on your device. Nothing is sent to OneFileClub or anyone else — there is no account, no cloud sync, no analytics.
Does it work offline?+
Yes. Once your personalised copy loads the first time, the entire tracker runs from a single HTML file. Airplane mode is fine.
What does 'personalised copy' mean?+
When you buy, OneFileClub stamps a private copy with your licence and deploys it to a unique URL just for you. You bookmark it, install it as an app, or save the file — and the file is yours, even if OneFileClub disappears tomorrow.
What is your refund policy?+
14 days, no questions asked. Email us, we'll process it and disable your private URL.
One payment.
A tank that stays alive.
We'll personalise a copy and email you a private link. Bookmark it, install it as an app, take it offline forever.
14-day refund · No subscription
