EqCalc vs cella
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
EqCalc
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EqCalc‑G is an educational and engineering reference tool for calculating gaseous chemical equilibrium using Gibbs free‑energy minimization. Designed for students, researchers, and practicing engineers, the app provides a fast, portable way to explore equilibrium behavior in hydrogen and hydrocarbon systems under ideal‑gas assumptions. Key Features: • Includes a publicly available thermochemical dataset derived from NASA curve‑fits of the NIST‑JANAF tables for selected species • Import your own thermochemical datasets in Aerotherm, Chemkin, or NASA CEA formats • Flexible reactant specification: - Define mixtures on a mole or mass basis - Or specify fuel mixture, air, and fuel‑air equivalence ratio • Export results easily by copying output to the clipboard for use in your favorite notes or spreadsheet apps Basic vs. Plus Version: The free Basic version supports fixed enthalpy and pressure equilibrium calculations. Upgrade to Plus version to unlock additional problem types: • Fixed temperature & pressure • Fixed entropy & pressure • Fixed internal energy & volume • Fixed temperature & volume • Fixed entropy & volume NASA/NIST Notice: Use of NASA and NIST thermochemical data does not imply endorsement, certification, recommendation, or approval of this app, its developer, or any results produced. NASA and NIST provide no warranties and assume no liability for the use of their data within this app. Privacy Policy: https://jtonouchi.github.io/EqCalc-G/privacy Terms and Conditions: https://jtonouchi.github.io/EqCalc-G/terms
cella
Explore crystal structures in interactive 3D. Visualize atomic arrangements, view different molecular models, and access a curated atlas of common materials. Supports CIF file import and export with a one-time purchase.
- Interactive 3D crystal exploration
- Fifteen visual Cell Notes
- Curated structure atlas
- Multiple view modes (ball-and-stick, space-filling)
- Unit cell and (hkl) plane visualization
- CIF file import and export (Pro)
- No ads, tracking, or analytics
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Open a supported CIF file and explore its structure in interactive 3D. cella brings crystal data, fifteen visual Cell Notes, and a curated structure atlas into one focused workspace for iPhone and iPad. READ THE STRUCTURE Fifteen Cell Notes connect familiar materials to the lattice beneath them. Follow salts, metals, carbon structures, and semiconductors through concise visual stories, then open the related crystal in 3D to inspect the model yourself. EXPLORE IN 3D • Rotate, zoom, and pan • Tap atoms to read element names, sites, and fractional coordinates • Switch between ball-and-stick, space-filling, and coordination-polyhedra views • Show the unit cell and (hkl) planes • Build a×b×c supercells USE THE BUILT-IN ATLAS Start with 20 free structures. The collection covers rock salt, diamond, graphite, fluorite, perovskites, common metals, and other teaching examples. Pro unlocks all 58 built-in structures. IMPORT AND EXPORT WITH PRO A one-time purchase unlocks supported CIF import, the full atlas, and high-resolution transparent PNG export. There is no subscription. CIF compatibility depends on file content. Unsupported or malformed files are reported in the app. Review labels and geometry before using exported images in research or publication. PRIVATE BY DESIGN No account, ads, tracking, or analytics. CIF files are processed on your device and never uploaded. Apple StoreKit may use an internet connection to load Pro availability, process purchases, or restore entitlements.
Screenshots
Verdict
The clearest difference is update cadence: cella at every 10 days against EqCalc's every 2 months. On price, ads, 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
Both are free to download. EqCalc sells 1 one-off in-app purchase and cella sells 1 one-off in-app purchase. Whichever you choose, the download price is not the number that matters.
EqCalc ships an update every 2 months, cella every 10 days. The most recent releases landed on November 5, 2026 and October 31, 2026 respectively.
| Parameter | EqCalc | cella |
|---|---|---|
| Price | Free | Free |
| Rating | — | 5.0 (1 ratings) — better |
| Positive reviews | — | 100.0% of reviews |
| Number of ratings | — | 1 — better |
| Update frequency | Every 2 months | Every 10 days — better |
| Ads | No | No |
| In-app purchases | Yes | Yes |
| Monetization | — | Freemium |
| Devices | iPhone, iPad | iPhone, iPad |
| Requires iOS | 18.2 | 17.0 — better |
| Further details — not scored | ||
| Size | 11 MB | 71 MB |
| Age rating | 17+ | 4+ |
| Developer | Jon Tonouchi | 武汉回到未来科技有限公司 |
In-app purchases
EqCalc
- Plus Version$2.99
cella
- cella Pro$5.99








