Diffu vs Commaday
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
Diffu
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Is there something you want to say but keep holding back? It won’t stay forever, so you can be a little more honest. Diffu is a public feed where you can put what you want to say into words and discover what others have shared. Start with Today’s Question when you need a prompt, or simply write whatever you want to say. A short sentence or a longer entry—either is welcome. Posts stay on the feed for a set amount of time and disappear when their public time ends. Your own posts remain available in your Records. ■ Write Freely What do you want to say right now? Share anything about daily life, work or school, love, family, relationships, interests, or whatever else is on your mind. ■ Today’s Question A new question opens every day. When you’re not sure what to write, start with a single sentence inspired by Today’s Question. ■ React and Send a Feeling React to other people’s posts to show that you relate. Send a Feeling lets you anonymously share a feeling and a short message. Depending on a post’s settings, reactions and feelings may extend its public time. ■ Records Calendar Days when you write freely or answer Today’s Question are marked on your calendar. See the days you recorded this month and how long you’ve kept your rhythm going. ■ Record Badges Your activities and small milestones in Diffu become badges, such as First Flame, Seven-Day Rhythm, and Flow of Records. Choose a featured badge to express yourself. ■ Posts Leave the Feed When Public Time Ends Diffu is neither a social network where everything stays public forever nor a private journal only you can see. It is a place where you can put your words out there for a while before they leave the public feed. For the words you’ve been holding back, let them out on Diffu—where they won’t stay forever. Privacy Policy: https://diffu.app/en/privacy Terms of Use (EULA): https://www.apple.com/legal/internet-services/itunes/dev/stdeula/
Commaday
This app helps you build a journaling habit by encouraging you to write just one sentence a day. It offers daily prompts and a unique 'comma' system to maintain streaks, even if you miss a day. Your entries are stored locally on your device for privacy.
- One-sentence daily entries
- Daily themes and keywords
- Streak tracking with 'commas'
- Calendar view of entries
- Local device storage
- Google Drive backup option
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A note first: the app's interface is entirely in Korean. There is no English UI yet. If you read Korean comfortably — or you're learning and want the immersion — it works as-is. I'd rather you know before installing. Inside the app you'll see its Korean name, 낙서장씨. How many journals have you started and left behind? Commaday is a diary built around one line a day. Too long to write, too imperfect to post, so you put it off — this app starts from the smallest habit instead. ■ One line a day One sentence is enough. You can attach a photo if you want. On days when nothing comes to mind, a prompt is waiting: 66 sentence prompts and 60 words run on separate cycles, so a given pairing takes nearly two years to come back. You can ignore both and write freely. If you'd like, a quiet reminder arrives each night at a time you choose. You can change it in settings. ■ The comma that keeps you going Write daily and your streak builds. Every seven days you earn a comma, and you can hold up to two. If you're running low, you can earn one by watching a single ad. Take a day off and a comma fills it in for you. And if a streak does end, every entry you wrote stays exactly where it is — nothing is deleted, and nothing counts down to a next goal. ■ Your time, gathered on a calendar The days you wrote are joined by a golden thread across the calendar. Look back after a month and the single lines have quietly become a story. ■ Your writing stays on your phone No account, no sign-up, no server of mine. Everything is stored on your device. An optional Google Drive backup lets you move your entries and photos to a new phone. ■ Premium (optional) · All 3 ways in one day — Freeform, Sentence, Word · 3 photos per entry · Write your own prompts and keep them · Export as PDF — each month on one calendar cover A one-time purchase. The free way you've been writing stays exactly as it is. Tonight, just one line.
Screenshots
Verdict
The clearest difference is device support: Diffu at 3 against Commaday's 1. On price, update cadence, ads and in-app purchases 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
Both are free to download. Diffu sells 6 in-app purchases, starting at $2.99 per month and Commaday sells 1 one-off in-app purchase. Whichever you choose, the download price is not the number that matters.
Diffu ships an update every 2 weeks, Commaday every 9 days. Both last shipped on November 5, 2026.
| Parameter | Diffu | Commaday |
|---|---|---|
| Price | Free | Free |
| Positive reviews | — | 100.0% of reviews |
| Update frequency | Every 2 weeks | Every 9 days — better |
| Ads | Yes | Yes |
| In-app purchases | Yes | Yes |
| Monetization | — | Ad-supported |
| Devices | iPhone, iPad, iPod — better | iPhone |
| Requires iOS | 15.0 — better | 16.4 |
| Further details — not scored | ||
| Size | 73 MB | 78 MB |
| Age rating | 17+ | 4+ |
| Developer | Jeong-Hwan Jang | WonHyeong Chang |
In-app purchases
Diffu
- Diffu Premium$2.991 Month
- Diffu Premium$29.991 Year
- 100 엠버$0.49
- 500 엠버$2.99
- 1000 엠버$6.99
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- 3000 엠버$19.99
Commaday
- Premium - All 3 Ways in one day$9.99








