Comparison

Empty vs Soln

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

Head to head
About

Empty

This app helps you track various fasting methods, including intermittent, circadian rhythm, and custom plans. It provides smart reminders and detailed progress views to support your health goals.

Highlights
  • Intermittent Fasting Tracking
  • Circadian Rhythm Fasting
  • Custom Fasting Plans
  • Smart Reminders
  • Progress Visualization
  • Fasting History
Features
Read full description

Empty is a simple and intuitive fasting tracker used for Intermittent, Circadian Rhythm, and Custom fasting. Choose your favorite fasting type and Empty will track and remind your ongoing progress. Empty supports the following fasting types: 16-Hour Intermittent Fasting (16/8): Popularized by Hugh Jackman (Wolverine) as a efficient way to remove extra weight. 16/8 fasting means eating within a window of eight hours each day such as from 12pm to 8pm and not eating during the remaining 16 hours. It helps get us into the sweet metabolic state of fat burning called Ketosis. Circadian Rhythm Fasting: Based on the research of Dr. Satchin Panda, the confining caloric consumption to about 12-hour period as people did just a century ago. It helps staving off high cholesterol, diabetes and obesity. Custom Fasting: Setup a custom program to meet your fasting goals. You choose your fasting hours per day, and days per week. Features: + Create Custom Fast + Smart Reminder (Remind you when your fasting completes even when the app is turn off) + Create your own custom alarms to fast + View the progress of the current fast + Show the full detail of your fasting days + Show the recent 7 fasts in chart and list + Get the average fasting time right in the Main Interface + Get the total hours of fasting in the Main Interface

About

Soln

Features
Read full description

Soln is a sleep engine built on cognitive load theory. Different from other sleep apps Most sleep apps are just players — they start audio and leave you to it. Soln calculates how hard it will be to fall asleep tonight, decides which layer to start at and how long to stay there, then stops when you're out. You don't have to manage anything. Five audio layers · Silent preparation — nothing playing, just space for your mind to settle · Minimal white noise — a steady background to mask outside noise · Heart rate-synced white noise — audio tempo follows your heart rate; as it slows, so does the sound · Tonal fade — frequency gradually drops, sliding your brain from alert to relaxed · Semantic drift — soft, loosely connected speech that gives your mind something to dissolve into instead of looping the same thought (paid) How long you spend on each layer isn't fixed — it depends on how you're doing tonight. Apple Watch auto-stop When you fall asleep, Apple Watch detects it. Soln fades the audio out over two seconds, then stops. No timer to set. No sudden silence to wake you (paid). Nightly assessment Before bed, based on today's mood and last night's sleep, Soln estimates how hard it'll be to fall asleep and gives you an optimal bedtime window and expected sleep onset time. In the morning, three scores: reaction, memory, and mood. Sleep well, score well. Sleep poorly, score reflects that. Straightforward. Full sleep history A three-color ring for each night. Long-press any day for that night's detail and sleep-onset timeline. One-time purchase Free for 7 days, full features included. After that, a one-time purchase permanently unlocks everything. Tied to your Apple ID — restore on any new device. No ongoing charges.

Screenshots

Empty4 screens
Soln4 screens

Verdict

The call

The clearest difference is ads: Soln at none against Empty's shown. Soln also leads on update cadence (every 3 weeks vs every 6 months). Empty's advantage is iOS requirement (15.6 vs 17.0). On price, in-app purchases 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. Empty sells 1 one-off in-app purchase and Soln sells 1 one-off in-app purchase. Whichever you choose, the download price is not the number that matters.

UpkeepUpdate frequency

Empty ships an update every 6 months, Soln every 3 weeks. The most recent releases landed on September 8, 2026 and September 9, 2026 respectively.

Scorecard3 real differences · 7 level
Empty versus Soln: the parameters behind the verdict, then further details
ParameterEmptySoln
PriceFreeFree
Rating4.5 (95 ratings) — better—
Positive reviews70.0% of reviews—
Number of ratings95 — better—
Update frequencyEvery 6 monthsEvery 3 weeks — better
AdsYesNo — better
In-app purchasesYesYes
MonetizationFree with in-app purchases—
DevicesiPhone, iPad, iPodiPhone, iPad, Apple Watch
Requires iOS15.6 — better17.0
Further details — not scored
Size14 MB3 MB
Age rating4+4+
DeveloperThang NguyenNan Yu

In-app purchases

1 purchases

Empty

One-time1
  • Pro Upgrade$4.99
1 purchases

Soln

One-time1
  • Unlock Soln$5.99

Questions

Is Empty free?
Empty is free to download, with in-app purchases available.
Is Soln free?
Soln is free to download, with in-app purchases available.
Do Empty or Soln have ads?
Empty shows ads; Soln does not.
Which is updated more often, Empty or Soln?
Empty ships an update every 6 months, and Soln every 3 weeks. Most recently, Empty was updated on September 8, 2026 and Soln on September 9, 2026.

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