Letter Explainer vs Optivolt
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
Letter Explainer
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Got an official letter and only understand half of it? Postklar explains it in plain words - in your language. HOW IT WORKS • Take a photo of the letter or open a PDF • Postklar reads it and explains it in 2-3 simple sentences • You see right away what to do, by when, and how much WHAT POSTKLAR DOES • Finds deadlines - even in the legal notice - and adds them to your calendar • Copy amounts, IBANs and reference numbers with one tap • Every number is checked against the letter; anything uncertain is flagged • Ask questions about the letter: “What happens if I don’t pay?” • Draft a reply: objection, payment plan, extension • Tells you when to get professional help - with links to free advice services YOUR DIGITAL FILING CABINET Every letter is filed automatically by sender: tax office, job centre, health insurer, landlord… Searchable, exportable as PDF and synced across your devices with iCloud. IN YOUR LANGUAGE Explanations in English, German, Russian, Ukrainian, Arabic, Turkish, Polish and Spanish. PRIVACY • Your letters are never stored on our servers and never used for AI training • Private mode: analysis only on your iPhone • No account, no email needed PRICING 3 letters free. Then Postklar Pro (monthly or yearly, up to 6 family members) or a pack of 5 letters. Postklar explains letters; it is not legal advice. Terms of Use: https://www.apple.com/legal/internet-services/itunes/dev/stdeula/
Optivolt
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The charger at your office is a perk. Optivolt helps you make the most of it. Tell Optivolt which days you're in the office, how many free charges you get each month and how much your commute uses. It builds the optimal plan for the whole month: which days to charge, how much battery you'll arrive with each morning, and how you'll finish the month. No spreadsheets. No guesswork. YOUR MONTH AT A GLANCE - A calendar you read in a second: office days, charge days and expected battery, evening by evening. - A battery chart with your charging threshold and month-end target always in view. - Your next charge up front, with arrival level before and after. REMINDERS THAT THINK FOR YOU - Get reminded to book the charger, as early as you like. - If the plan changes and a booked charge is no longer needed, Optivolt tells you in time to cancel it. - On charge-day mornings at 7:00, a heads-up that today is the day. - Mark a charge as booked right from the notification. ALWAYS IN SYNC WITH REALITY Took a detour? Charged at home? Enter the actual value and Optivolt instantly recalculates the rest of the month. Force a charge, skip one, and save sessions when you don't need them. OPTIVOLT PRO One purchase. Yours forever. No subscription. - Corrections with actual battery levels, extra consumption and home charging. - Every month: plan ahead and look back. - Default office days that fill in your calendar automatically. - History with a chart of your charges over the last year. - A beautifully designed monthly PDF report, ready to share. DESIGNED FOR iOS 26 A Liquid Glass interface, light and dark mode, and your data stays yours — on your iPhone and in your iCloud. No account, no ads, no tracking. Optivolt. The right charge, at the optimal time.
Screenshots
Verdict
The clearest difference is iOS requirement: Letter Explainer at 17.0 against Optivolt's 26.0. 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. Letter Explainer sells 3 in-app purchases, starting at $3.99 per month and Optivolt sells 1 one-off in-app purchase. Whichever you choose, the download price is not the number that matters.
| Parameter | Letter Explainer | Optivolt |
|---|---|---|
| Price | Free | Free |
| Update frequency | Every 5 days | — |
| Ads | No | No |
| In-app purchases | Yes | Yes |
| Devices | iPhone | iPhone, iPad — better |
| Requires iOS | 17.0 — better | 26.0 |
| Further details — not scored | ||
| Size | 22 MB | 2 MB |
| Age rating | 4+ | 4+ |
| Developer | Armen Ter-Oganezov | Stefano Ferrario |
In-app purchases
Letter Explainer
- Postklar Pro Monthly$3.991 Month
- Postklar Pro Yearly7 Days trial$24.991 Year
- 5 Scans$2.99
Optivolt
- Optivolt Pro$2.99









