OIO vs Letter
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
OIO
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OIO 是一个轻量的生活笔记工具。 随手记录生活、想法和片段,AI 会把你的真实记录整理成自然的目标语言,让笔记也成为属于你自己的语言学习素材。 记录生活,顺便学会表达。 Terms of Use (EULA): https://www.apple.com/legal/internet-services/itunes/dev/stdeula/
Letter
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Briefo: Letter Write, Post Mail makes it simple to create a letter digitally and send physical mail worldwide. Write and customize your document, choose a template, add a signature, select print and delivery options, and track your order from one place. Whether you want to send a personal letter, card, document, or other written correspondence, Briefo combines a practical letter editor with physical postal delivery. Prepare your mail without printing pages, preparing an envelope, or visiting a mailbox yourself. WRITE AND CUSTOMIZE YOUR LETTER Create a letter with the editor and customize your text before sending. Choose a template, prepare a multi-page letter, add page numbers when needed, or save your work as a draft and return later. Templates can help with common personal and everyday correspondence, including cancellation notices, complaints, requests, authorizations, formal notices, and personal letters across Europe and other destinations worldwide. ADD YOUR SIGNATURE Personalize your correspondence by uploading your signature as an image or drawing a hand signature directly for your letter. SEND PHYSICAL MAIL WORLDWIDE Briefo turns the letter you prepare digitally into physical mail for delivery to your selected destination. Save sender and recipient details to make preparing future letters more convenient. Briefo can be used for personal mail and correspondence addressed to military or army recipients, as well as jail, prison, or inmate correspondence where applicable. Institutions and destinations may have their own incoming mail rules, and Briefo does not guarantee acceptance or delivery by a particular recipient or institution. TRACK YOUR ORDER Use the postal tracker to track your order and receive order notifications. Keep sent letters organized and view your letter list inside the app. Features: * Write and customize letters * Select a letter template * Create multi-page letters and add page numbers * Upload a signature image or draw a hand signature * Choose black-and-white or color printing * Select available delivery and layout options * Save letters as drafts * Save recipients and senders * Track orders with the postal tracker * Receive order notifications * Export letters as PDF * Sync across devices * Send physical mail worldwide FREE ACCESS Free users can view their letter list and create and save recipient, sender, and signature information. PREMIUM ACCESS Sending physical letters requires sufficient credits. Credits can be purchased through in-app purchases. The required credits for each letter are calculated instantly based on that order, including page count, destination, delivery options, and layout options. You can see the calculated credit requirement before sending. IMPORTANT DISCLAIMER Briefo is a service for preparing and sending physical correspondence. Delivery and acceptance may depend on the destination, postal services, recipient, institution, and applicable mail rules. References to military, army, jail, prison, or inmate mail describe possible correspondence use cases and do not imply affiliation with or endorsement by any government, military, correctional institution, postal authority, or other third party. Privacy Policy: getbriefo.com/en/privacy Terms of Use: getbriefo.com/en/terms Support: support@getbriefo.com
Screenshots
Verdict
The clearest difference is in-app purchases: OIO at none against Letter's 6. On price, update cadence, ads 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 sells 6 one-off in-app purchases. OIO asks for nothing beyond the download.
OIO ships an update every 3 days, Letter every 5 days. The most recent releases landed on October 1, 2026 and September 28, 2026 respectively.
| Parameter | OIO | Letter |
|---|---|---|
| Price | Free | Free |
| Update frequency | Every 3 days — better | Every 5 days |
| Ads | No | No |
| In-app purchases | No — better | Yes |
| Devices | iPhone, iPad — better | iPhone |
| Requires iOS | 16.4 | 16.4 |
| Further details — not scored | ||
| Size | 41 MB | 70 MB |
| Age rating | 4+ | 4+ |
| Developer | Yongjia Yueyan Technology Co., Ltd | VUNYO |
In-app purchases
OIO
No in-app purchases
Letter
- Credit$1.99
- Credit$4.99
- Credit$6.99
Show 3 moreShow fewer
- Credit$9.99
- Credit$19.99
- Credit$49.99









