# ToDo Calendar vs Deadline Backsolve

The clearest difference is price: ToDo Calendar at Free against Deadline Backsolve's $0.99. Deadline Backsolve's advantage is in-app purchases (none vs 1) and ads (none vs shown). On update cadence, device support and iOS requirement there is nothing between them.

ToDo Calendar is free to download; Deadline Backsolve costs $0.99 up front. ToDo Calendar sells 1 in-app purchase, starting at $2.99 per month. Deadline Backsolve asks for nothing beyond the download.

ToDo Calendar ships an update every 2 weeks, Deadline Backsolve weekly. The most recent releases landed on November 3, 2026 and October 31, 2026 respectively.

## The numbers

| Metric | ToDo Calendar | Deadline Backsolve |
| --- | --- | --- |
| Price | **Free** | $0.99 |
| Rating | **[4.5 (11 ratings)](https://appshunter.io/ios/app/todo-calendar-dolfy/id6449158861/reviews)** | — |
| Number of ratings | **11** | — |
| Positive reviews | 82.2% of reviews | **100.0% of reviews** |
| In-app purchases | Yes | **No** |
| Ads | Yes | **No** |
| Update frequency | Every 2 weeks | **Weekly** |
| Monetization | **Free with in-app purchases** | Paid |
| Size | 27 MB | 4 MB |
| Requires iOS | 18.0 | **17.0** |
| Devices | iPhone, iPad | iPhone, iPad |
| Age rating | 4+ | 4+ |
| Developer | [TyabaApp](https://appshunter.io/developer/1536873203) | [Daisuke Yamaguchi](https://appshunter.io/developer/880950899) |

## What reviewers say

### ToDo Calendar

[App page](https://appshunter.io/ios/app/todo-calendar-dolfy/id6449158861)

This app combines a calendar and task manager for streamlined daily planning. It offers a unified view of appointments and to-dos, with customizable features like holiday integration and dark mode. Stay organized with smart notifications and recurring event options.

**Highlights:** Integrated scheduling and to-dos, Holiday and custom date customization, Dark mode and font flexibility, Smart notifications and reminders, Recurring event setup, Device calendar sync, Quick glance widget

**Features:** Vision Pro support, iPhone Duo support

**In-app purchases (1)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Monthly Subscription | $2.99 | per month |


### Deadline Backsolve

[App page](https://appshunter.io/ios/app/deadline-backsolve-planner/id6796252958)

This app helps you adjust project plans when deadlines are at risk. It calculates the shortfall and suggests concrete adjustments like extending deadlines or reducing scope. The interface is currently in Japanese only.

**Highlights:** Calculates shortfall and suggests fixes, Adjusts plans based on available time, Learns user's real work pace, Offers recovery plan options, Focus timer that survives crashes, Offline functionality, JSON export/import for data transfer

**Features:** macOS Compatibility, Vision Pro support

**In-app purchases:** none


## Frequently asked questions

### Is ToDo Calendar free?

ToDo Calendar is free to download, with in-app purchases available.

### Is Deadline Backsolve free?

Deadline Backsolve costs $0.99, with no in-app purchases.

### Do ToDo Calendar or Deadline Backsolve have ads?

ToDo Calendar shows ads; Deadline Backsolve does not.

### Which is updated more often, ToDo Calendar or Deadline Backsolve?

ToDo Calendar ships an update every 2 weeks, and Deadline Backsolve weekly. Most recently, ToDo Calendar was updated on November 3, 2026 and Deadline Backsolve on October 31, 2026.

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*Compared by [AppsHunter](https://appshunter.io/) from daily US App Store data. Review summaries are generated from verbatim App Store reviews.*