Julianator vs Blue Def Decoder
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
Julianator
Easily convert dates between the Gregorian calendar and the Julian Day of Year (ordinal date). This tool is useful for systems that use day-of-year numbering, such as mainframes, military, and food industries. It offers a clean interface, monthly views, and widgets for quick access.
- Gregorian to Julian Day of Year conversion
- Julian Day of Year to Gregorian conversion
- Monthly calendar view
- Home Screen widgets
- Lock Screen widgets
- Watch app with complications
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This app converts a date between Julian Day of Year and Gregorian. For example, September 11, 2022 converts to 2022-254 and 2022-254 converts to September 11, 2022. This app will convert both directions. Julian Date for this app refers to the day-of-year number (more properly, the ordinal date) in the Gregorian calendar, often used in mainframe computer systems, the military, and the food industry. (Note: this app does not used the term Julian Date to refer to the astronomy definition which is calculated from 4713 BC) Features a simple clean interface with pickers for the dates. The app also features a monthly view allowing a quick view of both Gregorian and Julian days for the entire month. Widgets are available for both the Home Screen and the Lock Screen to display the current day of year. A Watch app is available that includes a date converter and complications to display the current day of year. Note: The app's icon does not change to reflect the current day. Privacy Policy: https://julianator.brightdaydigital.com/privacy Terms of Service: https://julianator.brightdaydigital.com/terms
Blue Def Decoder
Instantly determine the freshness of your Diesel Exhaust Fluid (DEF) by entering the code from your container. This app helps you confirm DEF hasn't expired, track shelf life, and verify vehicle compliance, removing guesswork for diesel vehicle owners.
- Check DEF freshness
- Enter 5-11 character codes
- View manufacturing date
- See freshness status
- Track shelf life
- Verify vehicle compliance
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Easily check the freshness of your Diesel Exhaust Fluid (DEF) with Blue Def Decoder. Enter the 5–11 character code printed on your DEF container — whether it’s the short date section or the full code — and instantly see the manufacturing date and freshness status. Use Blue Def Decoder to: Confirm your DEF hasn’t expired Track shelf life for storage Verify compliance for your vehicle Blue Def Decoder saves you time and removes the guesswork from DEF code verification. Perfect for Sprinter van owners, diesel truck drivers, and anyone who needs quick, accurate results.
Screenshots
Verdict
The clearest difference is rating: Julianator at 4.7 against Blue Def Decoder's 3.0. Julianator also leads on ratings volume (117 vs 6) and price ($0.99 vs $3.99). Blue Def Decoder's advantage is iOS requirement (15.1 vs 17.4). On update cadence, ads, in-app purchases and chart position 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
Julianator costs $0.99 and Blue Def Decoder $3.99 up front. Neither carries in-app purchases, so what you see is what you pay.
Julianator holds the better App Store score, 4.7 against 3.0. That said, the two scores are not equally well evidenced: Julianator has 117 ratings behind it against 6, so its average is the more settled of the two. Written reviews point the same way: 70% of Julianator's written reviews are positive against 60% of Blue Def Decoder's.
Julianator ships an update every 3 months, Blue Def Decoder every 5 months. The most recent releases landed on October 10, 2026 and October 9, 2026 respectively.
| Parameter | Julianator | Blue Def Decoder |
|---|---|---|
| Price | $0.99 — better | $3.99 |
| Rating | 4.7 (117 ratings) — better | 3.0 (6 ratings) |
| Positive reviews | 70.4% of reviews — better | 60.0% of reviews |
| Number of ratings | 117 — better | 6 |
| Update frequency | Every 3 months — better | Every 5 months |
| Ads | No | No |
| In-app purchases | No | No |
| Monetization | Free — better | Paid |
| Best chart rank | #183 | #101 — better |
| Devices | iPhone, iPad, Apple Watch — better | iPhone, iPod |
| Requires iOS | 17.4 | 15.1 — better |
| Further details — not scored | ||
| Size | 4 MB | 20 MB |
| Age rating | 4+ | 4+ |
| Developer | Bright Day Digital LLC | Mako Technology Labs |
Customer experience
Julianator
Blue Def Decoder
In-app purchases
Julianator
No in-app purchases
Blue Def Decoder
No in-app purchases
Questions
Is Julianator free?
Is Blue Def Decoder free?
Which has better reviews, Julianator or Blue Def Decoder?
Do Julianator or Blue Def Decoder have ads?
Which is updated more often, Julianator or Blue Def Decoder?
Which is more popular, Julianator or Blue Def Decoder?
Other comparisons
