Comparison

MermaidEditor vs Happy

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

Head to head
About

MermaidEditor

Create and edit diagrams and charts using mermaid-js syntax with real-time preview. Export your creations as PNG or SVG files and share them across all your Apple devices.

Highlights
  • Mermaid-js syntax highlighting
  • Code completion
  • Instant preview
  • Export to PNG/SVG
  • Cross-device editing
  • QuickLook preview extension
Features
Read full description

MermaidEditor is a diagram and chart editor, powered by mermaid-js. And MermaidEditor supports iPhone, iPad and Mac, with one app you can edit diagram everywhere on any device. MermaidEditor supports mermaid-js syntax highlighting and code completion, so it can help writing diagram and chart clearly, easily and quickly. You can also easily export charts as PNG images or SVG files from the editor, or share image to other people with system actions. √ All Platforms - Both Mobile and Desktop platforms supported, you can edit diagram documents on iPhone, iPad or Mac - Document browser based app, easily edit files on device and sync document between devices - Multiple windows ready, it makes the editor more powerful on iPadOS - Keyboard shortcuts ready on iPadOS with keyboard connected √ Powerful Editor - Syntax Highlighting for mermaid-js grammar - Auto Completion in editor helps typing keywords quickly - Code Snippets likes parallel block in sequence diagram makes life easier - Instant Parsing Error indicator for locating syntax error √ Instant Preview - Auto Generated Preview when typing in editor - Zoom and Pan to move preview for checking diagram's detail - With Scroll wheel it can be easily zoom diagram on macOS √ Integrated Extensions - Thumbnail support, every .mmd file will has its own thumbnail when saving file - QuickLook Preview extension helps you preview mermaid document in Files app on iPhone or iPad and Finder on macOS √ Sharing - Save diagram document as its source with .mmd extension - Export diagram to PNG image or SVG file with one click For mermaid-js grammar, please visit https://mermaid-js.github.io/mermaid/ for documentation.

About

Happy

This app provides a secure mobile interface for AI coding assistants, allowing you to continue sessions and monitor progress from anywhere. It features end-to-end encryption and a zero-knowledge architecture for ultimate privacy. Seamlessly switch between desktop and mobile for uninterrupted AI coding.

Highlights
  • Seamless desktop and mobile session continuation
  • Push notifications for AI tasks
  • Offline access to conversation history
  • End-to-end encryption for code privacy
  • Real-time streaming of AI responses
  • Zero-knowledge architecture
Features
Read full description

Your coding agent shouldn't wait for you to get back to your desk. A task can run for an hour and then stop five minutes in to ask for permission or a decision. Happy lets you answer from your phone, and the same agent carries on in the same repository with the same tools and context. Happy is the mobile app for Claude Code and Codex. The agents keep running on your own computer, and your phone is how you start them, steer them and review their work. WHAT YOU CAN DO FROM YOUR PHONE • Start a new session or pick up one you began at your desk • Get notified when an agent needs input or finishes • Approve or deny permission requests, or let a session run in Auto mode • Choose the model and reasoning effort from the providers set up on your computer • Review changes: a file list, colored diffs, and the full set of changes on a branch • Attach a screenshot or photo to your prompt • Browse sessions in one list or grouped by project, with each checkout's chats as tabs • Open a side chat next to a session without losing your place • Drafts follow you between your phone and your computer HOW IT WORKS Happy runs on your computer, and this app connects to it. 1. Install Happy Desktop from happy.engineering, or if you prefer the terminal, run: npm install -g happy 2. Create an account in the app. You don't need an email address or a password. 3. Scan the QR code your computer shows to link it to your phone. Then start a session from either device. What you see on your phone is the same live session that's running on your computer. YOU WILL NEED • A computer running Happy Desktop or the Happy CLI • Access to the coding agents you want to use, such as a Claude or ChatGPT/Codex plan or API key. Happy uses your existing accounts. PRIVATE BY DESIGN Sessions are end-to-end encrypted. Your code, agent and encryption keys stay on your devices. Happy's servers only relay and store encrypted session data and can't read your prompts, responses or code. OPEN SOURCE The app, the CLI and the server are MIT-licensed and on GitHub. Read the code, run your own build or host your own server. ALSO ON DESKTOP Happy Desktop adds a harness that works across providers and lets you switch models in the middle of a task. The sessions it starts show up on your phone too. Happy is an independent project. It is not affiliated with or endorsed by Anthropic or OpenAI. Claude and Claude Code are trademarks of Anthropic. Codex and ChatGPT are trademarks of OpenAI. Privacy Policy: https://happy.engineering/privacy Terms of Use (EULA): https://www.apple.com/legal/internet-services/itunes/dev/stdeula/

Screenshots

MermaidEditor3 screens
Happy4 screens

Verdict

The call

The clearest difference is review sentiment: Happy at 72% against MermaidEditor's 14%. Happy also leads on price (Free vs $3.99) and rating (4.9 vs 2.3). MermaidEditor's advantage is in-app purchases (none vs 1). On ads, chart position, device support and iOS requirement 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

Happy is free to download; MermaidEditor costs $3.99 up front. Happy sells 1 in-app purchase, starting at $19.99 per month. MermaidEditor asks for nothing beyond the download.

ReceptionRating · Positive reviews · Number of ratings

Happy holds the better App Store score, 4.9 against 2.3. That said, the two scores are not equally well evidenced: Happy has 1K ratings behind it against 10, so its average is the more settled of the two. Written reviews point the same way: 14% of MermaidEditor's written reviews are positive against 72% of Happy's.

UpkeepUpdate frequency

MermaidEditor ships an update every 3 weeks, Happy weekly. The most recent releases landed on October 13, 2026 and October 14, 2026 respectively.

Scorecard7 real differences · 4 level
MermaidEditor versus Happy: the parameters behind the verdict, then further details
ParameterMermaidEditorHappy
Price$3.99Free — better
Rating2.3 (10 ratings)4.9 (1K ratings) — better
Positive reviews13.8% of reviews71.6% of reviews — better
Number of ratings101K — better
Update frequencyEvery 3 weeksWeekly — better
AdsNoNo
In-app purchasesNo — betterYes
MonetizationPaidFree with in-app purchases — better
Best chart rank#113#80 — better
DevicesiPhone, iPad, iPod, Mac — betteriPhone, iPad, iPod
Requires iOS14.0 — better15.1
Further details — not scored
Size125 MB98 MB
Age rating4+4+
Developer基伟 徐Bulka, LLC

Customer experience

MermaidEditor

All ratings10 ratings
Positive30.0%
Neutral0.0%
Negative70.0%
Written reviews29 reviews
Positive13.8%
Neutral13.8%
Negative72.4%

Happy

All ratings1,024 ratings
Positive96.7%
Neutral1.0%
Negative2.3%
Written reviews67 reviews
Positive71.6%
Neutral10.4%
Negative17.9%

In-app purchases

None

MermaidEditor

No in-app purchases

1 purchases

Happy

Subscriptions1
  • Plus Plus Monthly$19.991 Month

Questions

Is MermaidEditor free?
MermaidEditor costs $3.99, with no in-app purchases.
Is Happy free?
Happy is free to download, with in-app purchases available.
Which has better reviews, MermaidEditor or Happy?
Happy is rated higher. MermaidEditor averages 2.3 out of 5 from 10 ratings, while Happy averages 4.9 from 1K ratings.
Do MermaidEditor or Happy have ads?
Neither MermaidEditor nor Happy shows ads.
Which is updated more often, MermaidEditor or Happy?
MermaidEditor ships an update every 3 weeks, and Happy weekly. Most recently, MermaidEditor was updated on October 13, 2026 and Happy on October 14, 2026.
Which is more popular, MermaidEditor or Happy?
MermaidEditor currently peaks at #113 in the App Store charts, and Happy at #80. Chart position reflects recent download velocity rather than total install base.

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