Comparison

CHALLNA vs Atto

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

Head to head
About

CHALLNA

This app helps you achieve precise timing for critical online events by displaying accurate server time, accounting for network latency. It offers one-touch presets for popular sites, countdown timers, and practice modes to improve your reaction speed for ticket sales, course registrations, and limited drops.

Highlights
  • Millisecond precision synchronization
  • One-touch server presets
  • Intuitive countdown timers
  • Click practice mode
  • Smart reminders and schedule registration
  • Direct site access
  • Dynamic Island support
Features
Read full description

β–  0.01 Seconds Make All the Difference. Have you ever missed out on popular concert tickets, course registrations, or limited-edition drops by a split second? Don’t rely on your phone’s local time. Check the "Real Server Time" of the site itself. 'CHALLNA' will drastically increase your success rate. β–  Why CHALLNA? (Key Features) 1. Millisecond(ms) Precision Synchronization We do more than just fetch server time. CHALLNA calculates network latency (RTT) and average transmission deviations in real-time to correct any errors. Find the "true" 0.01 second with Korea’s highest level of precision. 2. One-Touch Server Presets Interpark, YES24, Melon Ticket, and even major university registration sites! No need to type addresses manually. Simply search to instantly register and track your desired server. 3. Intuitive Countdown & Target Setting Set your goal time and watch the countdown in real-time down to the millisecond. Stay perfectly prepared for that high-pressure moment right before the opening. 4. Click Practice for Real-World Reflexes Theory is different from practice! Use the built-in 'On-the-Dot Click Practice' to check your reaction speed and master the feeling of clicking at exactly 0.00 seconds. 5. Smart Reminders & Schedule Registration (HOT!) Register your important ticketing or course registration schedules. We’ll make sure you’re ready with custom notifications before your target time, even in your busy daily life. 6. Direct Site Access Why check the time and switch apps separately? CHALLNA provides direct outlinks to the sites, shortening your access time to the absolute minimum. 7. Dynamic Island Support Keep tracking the time via Dynamic Island even while moving to the ticketing site, ensuring you never miss the countdown. (Available on iPhone 14 Pro and later models) β–  Highly Recommended For: β€’ Concert fans tired of losing out in "Blood-keting" (bloody ticketing). β€’ Students desperate to secure popular university courses. β€’ Anyone needing perfect timing for holiday train bookings or limited drops. β€’ Perfectionists who won't settle for even a 0.01-second error. β–  Please Note: β€’ Minor errors may occur depending on network conditions. We recommend using a stable Wi-Fi, 5G, or LTE environment. β€’ For the best results, be sure to use the 'Click Practice' feature in advance! Download 'CHALLNA' now and experience the miracle of 0.01 seconds!

About

Atto

This utility app precisely measures and displays server clock times for time-sensitive events like ticket drops. It offers advanced features to correct for device drift and ensure accurate countdowns, even while using other applications.

Highlights
  • Server clock synchronization
  • Millisecond precision countdown
  • Device drift correction
  • Picture-in-Picture mode
  • Haptic and sound alerts
  • Practice mode for timing
  • Supports over 300 time sources
Features
Read full description

A ticket drop is decided in milliseconds, not seconds. The queue opens on the booking server's clock, not your phone's. The two are usually tens to hundreds of milliseconds apart, and that gap decides your place in line. Atto reads the server's clock directly, and shows you how well it read it. Measuring server time An HTTP Date header only resolves to the second, so one read tells you Β±500ms and no more. Atto probes at 137ms intervals so each request lands on a different phase inside the second. Once the offset narrows, it predicts when the server's second will roll over and aims at that edge. Twenty overlapping measurements fold the error down to the round trip. The error bar stays visible Instead of a label like "high accuracy" you get the measured figure: Β±23ms. Sample count, rejected samples, best round trip, and how far this server runs from national standard time are all on screen. Cached responses get dropped When a CDN answers instead of the origin, the clock inside that response is frozen at the moment it was stored. Atto checks the Age and cache headers and keeps those responses out of the average. Device drift correction Your phone's oscillator runs seconds off per day. Atto measures the slope between syncs, extrapolates it to now, and re-syncs every two minutes while you wait. Picture in Picture Press Start and a Picture in Picture window floats above your other apps. Show a decreasing countdown or a corrected wall clock that advances toward your configured target, with three-digit milliseconds. Keep the timing in sight while using a booking app or webpage. Haptics and sound Taps begin at the lead time you set and end with one hard hit at zero. The whole pattern goes to Core Haptics up front rather than a timer, so zero does not move even if the screen stutters. Sound is optional and plays through the silent switch. Practice mode A recommended lead time is somebody else's number. Measure the gap between the buzz and your tap actually registering, then apply your own median. Time sources Over 300 sources across 14 regions, including Ticketmaster, AXS, StubHub, Interpark, e+, tixCraft and Damai, plus course registration sites and sneaker drops. Standard-time servers like NIST, NPL, PTB, NICT and KRISS are there too, and you can type any address yourself. Free and paid Everything that decides whether you get the ticket is free: full sync accuracy, drift correction, the on-screen countdown, haptics, every time source, practice mode. One rewarded ad floats a single countdown in a PiP window. A one-time purchase removes ads and keeps PiP unlocked. It is not a subscription. Reading a clock takes one HEAD request. Atto never asks for an account and takes no part in the booking itself. English, ν•œκ΅­μ–΄, ζ—₯本θͺž

Screenshots

CHALLNA4 screens
Atto4 screens

Verdict

The call

The clearest difference is in-app purchases: CHALLNA at none against Atto's 1. CHALLNA also leads on ads (none vs shown). Atto's advantage is update cadence (every 4 days vs every 2 weeks). On price, review sentiment, device support and iOS requirement there is nothing between them.

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

CostPrice Β· In-app purchases Β· Ads Β· Monetization

Both are free to download. Atto sells 1 one-off in-app purchase. CHALLNA asks for nothing beyond the download.

UpkeepUpdate frequency

CHALLNA ships an update every 2 weeks, Atto every 4 days. The most recent releases landed on October 31, 2026 and November 4, 2026 respectively.

Scorecard4 real differences Β· 4 level
CHALLNA versus Atto: the parameters behind the verdict, then further details
ParameterCHALLNAAtto
PriceFreeFree
Positive reviews100.0% of reviews100.0% of reviews
Update frequencyEvery 2 weeksEvery 4 days β€” better
AdsNo β€” betterYes
In-app purchasesNo β€” betterYes
MonetizationFree β€” betterFree with in-app purchases
DevicesiPhone, iPad β€” betteriPhone
Requires iOS16.6 β€” better17.0
Further details β€” not scored
Size38 MB11 MB
Age rating4+4+
DeveloperRYNYULBeomjin In

Customer experience

CHALLNA

Written reviews3 reviews
Positive100.0%
Neutral0.0%
Negative0.0%

Atto

Written reviews9 reviews
Positive100.0%
Neutral0.0%
Negative0.0%

In-app purchases

None

CHALLNA

No in-app purchases

1 purchases

Atto

One-time1
  • Atto Pro$1.99

Questions

Is CHALLNA free?
CHALLNA is free to download, with no in-app purchases.
Is Atto free?
Atto is free to download, with in-app purchases available.
Do CHALLNA or Atto have ads?
Atto shows ads; CHALLNA does not.
Which is updated more often, CHALLNA or Atto?
CHALLNA ships an update every 2 weeks, and Atto every 4 days. Most recently, CHALLNA was updated on October 31, 2026 and Atto on November 4, 2026.

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