Comparison

Acid Base pH vs Chess Opener PRO

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

Head to head
About

Acid Base pH

Accurately estimate pH values for acid-base aqueous systems. Calculate pH for weak and strong acids/bases, plot titration curves, and find equivalent points. Export data and find titrant volumes for desired pH.

Highlights
  • Estimate pH of acid-base solutions
  • Plot titration curves
  • Find pH and titrant volume at equivalent points
  • Export titration plots as image or data
  • Calculate titrant volume for desired pH
  • Includes list of common indicators
Features
Read full description

Acid Base pH is the ultimate tool for accurate estimation of pH values of acid – base aqueous systems. This application calculates pH values of solutions of weak and strong, monoprotic and polyprotic acids and bases and additionally builds titration curves and provides pH and titrant volume values at equivalent points. Layout of "Acid Base pH". Screen is divided by two sides: acidic (left) and basic (right), comprising of initial data of solutions, such as molar concentration, volume, proticity and equilibrium constants of first three dissociations. The upper, main field on each side allows to choose if the compound is titrant or analyte and the right field in the second row allows to choose proticity and weakness of acid or base. Important: Titrant compound, by default, can be only monoprotic and strong. When molar concentration of only one initial solution is provided (acid or base side), the application will estimate pH of the single solution. On the other hand, if both solution concentrations are provided, then application will be able to draw titration plot (“Plot” option in the navigation bar), based on titrant-analyte parameters as well as to provide pH and titrant volume values at equivalent points. Furthermore, the plot of titration curve can be exported as an image or as text worksheet. Additionally, it is possible to find titrant volume needed to achieve desired pH value, by entering the pH value to the corresponding field and pressing “Calculate” button. Application features. ·Estimation of solutions pH values is based on advanced quantitative chemical analysis which allows simultaneous calculation of all dissociation stages of acid and base and water dissociation (Kw). ·Application can plot titration curve and export it as an image or data file to the “Acid Base pH” directory in the “Documents” fiolder. ·Application provides pH and titrant volume values at equivalent points. ·Water dissociation constant (Kw) can be adjusted to meet any custom conditions (temperature, etc.). ·Application is able to estimate the titrant volume needed to achieve desired pH values (within titration range), that is particularly useful for buffer preparation. ·The dissociation constants fields accept both formats: 1) pK values (-log(K)) as a simple decimal values and 2) regular K values, in scientific format only, that requires including of exponential part “e” (for example: 1e-5 instead of 0.00001, or 2.5e0 instead of 2.5). Empty dissociation constant field would imply that this dissociation step is “strong” or complete. ·Long press on “Calculate” button shows pOH and [H+] and [OH-] concentration values, corresponding to the current pH. · Application provides list of commonly used indicators and presents color transformations on top of titration curve. Important points. ·The user must provide both initial molar concentrations of acid and base in order to get the titration curve plotted. ·To get the specific pH value of the mixture, the user must provide initial volumes of acid and base solutions, otherwise pH at equimolar point will be estimated! ·If user updates any of the required data, the program will not start to plot titration curve until user press “Calculate” button and only if the update is accepted. ·Equivalent point is represented by particularly big jump in pH at almost no change in volume, making impractical any precise titrant volume estimation in the close proximity to the point. ·Initial concentrations of acid or base must be above 0.5 µM. ·Info for equivalent points is provided on the base of molar ratios only! ·Application assigns dot as a decimal separator.

About

Chess Opener PRO

Master chess openings with a comprehensive trainer and explorer. Analyze grandmaster repertoires, build your own opening lines, and memorize variations with interactive training. Works offline with no ads.

Highlights
  • Chess opening tree with statistics
  • Encyclopedia of Chess Openings (ECO)
  • Grandmaster repertoire database
  • Stockfish engine analysis
  • Interactive opening trainer
  • Build and manage opening repertoire
  • PGN import/export
Features
Read full description

Features: - Chess opening tree with game statistics - The Encyclopedia of Chess Openings (ECO) - Database of top 100+ grandmasters’ repertoires - Stockfish chess engine analysis - Compare ECO, opening tree and engine moves side by side in any position - Import and export chess openings in PGN format - Build your own opening repertoire - Add or edit comments on moves - Automatically classify any sequence of moves using the ECO system - Chess opening explorer highlights moves already in your repertoire - Chess database includes all transpositions - Interactive trainer to memorize your chess openings and variations - Train multiple variations at once against random opponent moves from your repertoire - Set up a starting position for training - Track your training progress - Customize chessboard colors and chess pieces - Supports dark mode - No ads - Works completely offline CHESS OPENING EXPLORER Search in the Encyclopedia of Chess Openings, browse the chess opening tree, explore the opening repertoires of famous chess grandmasters, or ask the chess engine to find the best moves. Swipe left or right to switch between the exploration features in any position. BUILD YOUR OPENING REPERTOIRE Add your favorite opening lines to your repertoire using the chess opening explorer or import your openings in PGN format from other chess programs. You can always edit the names of your openings and organize them in your repertoire. OPENING TRAINER A simple and efficient method to memorize variations of openings in your repertoire. You can train either white’s moves or black’s moves only or both. Optionally, you can train all variations at once. The trainer chooses the opponent’s moves randomly from your opening repertoire. Chess Opener tracks your progress and shows your stats.

Screenshots

Acid Base pH4 screens
Chess Opener PRO4 screens

Verdict

The call

The clearest difference is rating: Acid Base pH at 5.0 against Chess Opener PRO's 4.4. Acid Base pH also leads on review sentiment (100% vs 76%) and price ($3.99 vs $8.99). Chess Opener PRO's advantage is ratings volume (79 vs 1) and update cadence (every 5 weeks vs every 3 months). On ads, in-app purchases, monetization model 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

Acid Base pH costs $3.99 and Chess Opener PRO $8.99 up front. Neither carries in-app purchases, so what you see is what you pay.

ReceptionRating · Positive reviews · Number of ratings

Acid Base pH holds the better App Store score, 5.0 against 4.4. That said, the two scores are not equally well evidenced: Chess Opener PRO has 79 ratings behind it against 1, so its average is the more settled of the two. Written reviews point the same way: 100% of Acid Base pH's written reviews are positive against 76% of Chess Opener PRO's.

UpkeepUpdate frequency

Acid Base pH ships an update every 3 months, Chess Opener PRO every 5 weeks. The most recent releases landed on November 6, 2026 and November 7, 2026 respectively.

Scorecard6 real differences · 4 level
Acid Base pH versus Chess Opener PRO: the parameters behind the verdict, then further details
ParameterAcid Base pHChess Opener PRO
Price$3.99 — better$8.99
Rating5.0 (1 ratings) — better4.4 (79 ratings)
Positive reviews100.0% of reviews — better75.9% of reviews
Number of ratings179 — better
Update frequencyEvery 3 monthsEvery 5 weeks — better
AdsNoNo
In-app purchasesNoNo
MonetizationPaidPaid
DevicesiPhone, iPadiPhone, iPad, iPod — better
Requires iOS17.115.1 — better
Further details — not scored
Size2 MB149 MB
Age rating4+4+
DeveloperRoman VolinskyStanislav Basovnik

Customer experience

Acid Base pH

All ratings1 ratings
Positive100.0%
Neutral0.0%
Negative0.0%
Written reviews1 reviews
Positive100.0%
Neutral0.0%
Negative0.0%

Chess Opener PRO

All ratings80 ratings
Positive83.8%
Neutral5.0%
Negative11.3%
Written reviews54 reviews
Positive75.9%
Neutral7.4%
Negative16.7%

Bugs and requests

Acid Base pH

Not enough reviews yet to summarise bugs or requests.

Chess Opener PRO

Reported bugs

6 issues
  • Invalid PGN import
  • Crashes quite often
  • Repeats same variation
  • Cannot review lines while training
  • App not functioning with iOS 16.7.4
Show 1 more
  • PGN import is tedious and doesn't support variants

Requested features

12 requests
  • Include position setting
  • Start study from a later position
  • Multiple folders for simultaneous practice
  • Option to switch between figure visibility modes (normal, queen pieces, none)
  • Blindfold practice option
Show 7 more
  • Show +1 for capturing a pawn
  • iCloud sync across devices
  • Organize repertoires (move, sort, add folders)
  • Predefine variants not to reappear during training
  • User guide or help information
  • Support for split screen
  • Fix compatibility with iOS 16.7.4

In-app purchases

None

Acid Base pH

No in-app purchases

None

Chess Opener PRO

No in-app purchases

Questions

Is Acid Base pH free?
Acid Base pH costs $3.99, with no in-app purchases.
Is Chess Opener PRO free?
Chess Opener PRO costs $8.99, with no in-app purchases.
Which has better reviews, Acid Base pH or Chess Opener PRO?
Acid Base pH is rated higher. Acid Base pH averages 5.0 out of 5 from 1 ratings, while Chess Opener PRO averages 4.4 from 79 ratings.
Do Acid Base pH or Chess Opener PRO have ads?
Neither Acid Base pH nor Chess Opener PRO shows ads.
Which is updated more often, Acid Base pH or Chess Opener PRO?
Acid Base pH ships an update every 3 months, and Chess Opener PRO every 5 weeks. Most recently, Acid Base pH was updated on November 6, 2026 and Chess Opener PRO on November 7, 2026.

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