Comparison

ByWhen vs Cairn

Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.

Head to head
About

ByWhen

Features
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A deadline is not just a date. It is a promise your future self needs help keeping. ByWhen helps you turn important tasks into practical reminder plans. Instead of relying on one alert, ByWhen looks at what needs to be done, when it is due, how long it may take, what kind of attention it needs, and when your day has realistic space for it. Add a task, set the due date, estimate the effort, choose the task type, and ByWhen helps you stay aware of the work before it turns into last-minute pressure. ByWhen is built for: - Work projects with real due dates - Assignments, exams, and study sessions - Calls, forms, paperwork, and admin tasks - Errands that need time away from home or work - Personal tasks that are easy to postpone - Daily, weekly, monthly, yearly, and selected-day routines DEADLINE PLANS ByWhen helps you think beyond a simple due date. It considers time remaining, estimated effort, task priority, task type, and available windows in your day. A short call can fit differently than a focused work session. An errand that requires leaving home can be treated differently from a quick task you can do during a break. REMINDERS WITH CONTEXT ByWhen keeps the deadline visible as time passes. It highlights whether a task is on track, needs attention, is at risk, or has become critical. If you do not act on a reminder right away, the task remains part of your plan so you can return to it later. OPEN-TIME PLANNING With your permission, ByWhen can use calendar busy blocks to avoid suggesting times that are already occupied. You can choose what to include, ignore imported blocks, and keep control of your schedule. ROUTINE SETTINGS Set your wake time, sleep time, work hours, and workdays so reminder timing fits your real life. ByWhen can avoid unhelpful times and protect parts of the day when reminders would not make sense. TASK TYPES Different tasks need different kinds of time. ByWhen supports task types such as focused work, admin, calls, study, errands, and away-from-home tasks. This helps ByWhen suggest more realistic moments instead of treating every reminder the same way. REPEATING TASKS Create repeating tasks for daily, weekly, monthly, yearly, or selected days of the week. When you complete a repeating task, ByWhen moves the next cycle forward so you are not reminded again for the period you already finished. QUICK ACTIONS Act from a reminder when possible. Start work, be reminded later, log time, or mark the task done so your plan can stay up to date. PRIVATE BY DESIGN ByWhen is built with privacy in mind. Your tasks, schedule blocks, routine settings, and reminder plans stay on your device. No account is required to start. If you choose to export a backup, it goes to your own selected destination. BYWHEN PREMIUM Your first 7 days are ByWhen Premium. During this time, all smart planning features are available. ByWhen Premium keeps every reminder active and unlocks the full planning experience, including unlimited active reminders, deadline plans, open-time planning, task-specific reminder styles, repeating tasks, quick actions, and routine personalization. After the first 7 days, your reminders stay safe, but Premium is required to keep all smart reminders active. Download ByWhen and give your deadlines a plan you can trust. Privacy Policy: https://nionlite.com/bywhen-privacy.html Terms of Use: https://nionlite.com/bywhen-terms.html

About

Cairn

Manage tasks and notes directly within your existing Markdown files. This app offers focused views, quick capture, and robust task management features, all while keeping your data private and locally stored. It integrates seamlessly with Obsidian and other file sync services.

Highlights
  • Native Markdown task and note management
  • Works with Obsidian vaults or any folder
  • Quick capture with date, tag, and priority parsing
  • Multiple task views (Today, Upcoming, Inbox, Pool)
  • Full support for sub-tasks and recurring tasks
  • Local reminders and Live Activity integration
  • Data stays local, no cloud sync required
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Cairn is a fast, native task and note companion that lives on top of the Markdown files you already own. Point it at your Obsidian vault — or any folder of Markdown notes — and your tasks and notes appear in clean, focused views. Everything you do in Cairn is written straight back to your files as plain text, in the Obsidian Tasks format. YOUR NOTES STAY YOURS • No account, no sign-up, no Cairn cloud database — your tasks live in your own files • Cairn does not send your notes or tasks to the developer • Careful, patch-based edits change only the content you touched, preserving the rest of your note • Works alongside Obsidian, iCloud Drive, Git, or any sync you already use CAPTURE, BROWSE, AND PLAN • Browse and edit Markdown notes directly in your vault • Quick capture into your daily note, with date, tag, and priority tokens parsed as you type • Choose where longer captures are saved • Today, Upcoming, Inbox, and Pool views, plus a global filter for folders, tags, dates, priority, and status • Full support for sub-tasks and task hierarchies • Recurring tasks in Obsidian Tasks format, with safe completion handling • Convert upcoming calendar events into tasks, or mirror your dated tasks into a calendar you choose (optional) STAY ON TRACK • Local reminders for due tasks — including sunrise-relative reminders computed entirely on your device • A Live Activity keeps today's progress on your Lock Screen and in the Dynamic Island • Home Screen widgets and a Control Center quick-capture control • Search across every task in your vault MADE FOR OBSIDIAN — NOT ONLY OBSIDIAN Cairn reads and writes the Obsidian Tasks plugin format (due, scheduled, start, and done dates, priorities, recurrence, tags), so your vault stays fully compatible with your desktop setup. Don't use Obsidian? Create a plain task folder in the Files app and Cairn works as a stand-alone Markdown to-do app. Cairn asks for access only to the folder you pick. Calendar access and location (used to compute local sunrise times) are optional and processed on your device. If you choose iCloud Drive or another Files or calendar provider, that provider's own sync and privacy terms apply.

Screenshots

ByWhen4 screens
Cairn4 screens

Verdict

The call

The clearest difference is in-app purchases: Cairn at none against ByWhen's 2. On price, update cadence, ads and device support there is nothing between them.

Scored on Price · Rating · Positive reviews · Number of ratings · Update frequency · Ads · In-app purchases · Monetization · Best chart rank · Devices · Requires iOS

CostPrice · In-app purchases · Ads · Monetization

Both are free to download. ByWhen sells 2 in-app purchases, starting at $4.99 per month. Cairn asks for nothing beyond the download.

UpkeepUpdate frequency

ByWhen ships an update every 3 days, Cairn every 5 days. The most recent releases landed on September 18, 2026 and October 1, 2026 respectively.

Scorecard1 real difference · 9 level
ByWhen versus Cairn: the parameters behind the verdict, then further details
ParameterByWhenCairn
PriceFreeFree
Rating—5.0 (1 ratings) — better
Positive reviews—100.0% of reviews
Number of ratings—1 — better
Update frequencyEvery 3 days — betterEvery 5 days
AdsNoNo
In-app purchasesYesNo — better
Monetization—Free
DevicesiPhoneiPhone, iPad — better
Requires iOS17.017.0
Further details — not scored
Size8 MB9 MB
Age rating4+4+
DeveloperNiONlite LLCYoung Hun JEONG

In-app purchases

2 purchases

ByWhen

Subscriptions2
  • Monthly Premium$4.991 Month
  • Annual Premium$39.991 Year
None

Cairn

No in-app purchases

Questions

Is ByWhen free?
ByWhen is free to download, with in-app purchases available.
Is Cairn free?
Cairn is free to download, with no in-app purchases.
Do ByWhen or Cairn have ads?
Neither ByWhen nor Cairn shows ads.
Which is updated more often, ByWhen or Cairn?
ByWhen ships an update every 3 days, and Cairn every 5 days. Most recently, ByWhen was updated on September 18, 2026 and Cairn on October 1, 2026.

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