Technical FAQ

How fast are lookups?

Target: < 2 seconds

DevLingo uses a tiered caching strategy to ensure fast responses:

Local Technical Vocabulary (Instant)

Contains 85+ commonly used development terms (API, library, deprecation, etc.)
Stored in a local SwiftData database
First lookup returns instantly, zero network latency

Cached Queries (< 500ms)

Previously looked-up words are read from local cache
Includes AI-generated definitions, examples, and pronunciation links
Accessible offline

New AI Queries (1-2 seconds)

Forwarded to the Claude API through Cloudflare Workers edge nodes
Includes full analysis, examples, synonyms, and pronunciation synthesis
Edge deployment ensures low latency

Where does pronunciation data come from?

DevLingo’s pronunciation is based on multiple authoritative sources:

Source Combination

Official documentation: Collected official pronunciations from Apple, Google, Meta, Amazon, etc. (AWS, iOS, and other terms)
YouGlish corpus: Sampled pronunciation patterns from real developer videos
Developer community consensus: Continuously updated through team feedback for unofficial term pronunciations
Human IPA annotation: All pronunciations are annotated with IPA (International Phonetic Alphabet) standards

Synthesis Technology

Engine: Google Cloud Text-to-Speech
Model: Neural voice model (more natural than traditional TTS)
Coverage: American and British English (switchable on demand)

Reporting Inaccurate Pronunciation

If you find a pronunciation error:

Click Report Issue on the learning card
Select Pronunciation
Provide what you believe is the correct pronunciation or a relevant source link

Community feedback helps us continuously improve.

How are cloud sync conflicts resolved?

DevLingo uses a last-write-wins sync strategy for multi-device editing:

How Sync Works

Client timestamp: Each time a Word Book entry is modified, a clientUpdatedAt timestamp is recorded
Cloud merge: When uploading to Cloudflare D1, timestamps are compared
Most recent wins: The version with the newer timestamp overwrites the older one
Offline support: Offline edits are automatically synced when the network is restored

Example Scenario

Scenario: Editing the same entry on two Macs simultaneously

Mac A: Adds a note “API design pattern” offline (2:00 PM)
Mac B: Updates the definition online (2:05 PM)
Sync result: Mac B’s update wins (later timestamp)

To keep both versions, create two separate entries in the Word Book.

Can I export Word Book data?

Currently Supported: CSV

Open Settings > Data > Export
Select CSV format
Export includes:
- Vocabulary
- Definitions
- Example sentences
- Learning tags (save date, review count)

CSV files are compatible with Excel, Google Sheets, and other tools.

Roadmap Features

Anki deck export: Convert to Anki format (.apkg) for spaced repetition learning
Notion database import: Import directly into Notion for integration with your personal knowledge base
JSON export: Full data export including all metadata

Which AI model is used for API calls?

Model: Claude (Anthropic)

DevLingo uses Claude as the backend AI model:

Why Claude:

Accuracy: Understanding of technical terms exceeds other models
Structured output: Supports JSON format responses for easy app display
Multilingual: Better understanding of code examples and mixed-language queries
Cost efficiency: Reasonable API pricing

What’s Included in Requests

The selected English vocabulary
Current app context (Xcode, Slack, etc.)
User language background (optional, for L1 interference correction)

Not included:

Document content (only the selected vocabulary is sent)
User identity information
Browsing history or app content

API Call Frequency

Free plan: 10/day
Pro plan: Unlimited
Team plan: Unlimited

Why isn’t it on the Mac App Store?

Main Reasons

Accessibility Permission UX
- The Accessibility permission cannot be gracefully requested from within the App Store
- DevLingo needs this permission for the global hotkey and cross-app text selection
- Direct download provides a better first-use experience
Faster Iteration
- Direct distribution doesn’t require waiting for App Store review (usually 1-2 days)
- Can quickly push bug fixes and new features
- Direct user feedback
Flexible Pricing
- App Store In-App Purchase has a 30% commission
- Direct sales and License Key model are more cost-effective
- Better pricing transparency

Future Possibility

Mac App Store listing conditions:

Apple improves the Accessibility permission request flow
Or DevLingo’s features evolve to no longer require Accessibility permission

For now, we prioritize direct distribution for a better user experience.

Are custom shortcuts supported?

Current Status

DevLingo uses a fixed global shortcut: ⌘⇧D (global lookup)

Planned Features

Custom global shortcut: Let users change to ⌘⇧E, ⌘⇧L, etc.
Shortcut profiles: Save and import preset configurations
App-level shortcut overrides: Define different shortcuts for specific apps

Temporary Workaround

If ⌘⇧D conflicts with another app:

Disable the conflicting app’s shortcut
Or remap in macOS System Settings
Use the menu bar icon to manually trigger lookups

Submit shortcut customization requests to: [email protected]

Where is data stored?

Local Storage (Device)

SwiftData database: Word Book, learning history, cached queries
Location: ~/Library/DevLingo/ (user-private, other apps cannot access)
Encryption: macOS file system encryption (FileVault)

Cloud Storage (User-Isolated)

Database: Cloudflare D1 (SQLite)
Cache: Cloudflare KV (for sessions and rate limiting)
Data centers: Global edge nodes, but user data is fully isolated by account
Encrypted transport: All communication uses TLS 1.3

Privacy Assurance

Data is isolated by user ID; DevLingo staff cannot access user data
Regular security audits
See the Privacy Policy for details

Data Deletion

After account deletion, all cloud and local data is permanently deleted within 30 days.