Tools for Mobile Developers

BY TOOLS.FUN  ·  MARCH 28, 2026  ·  4 min read

Mobile developers work across native iOS, Android, and cross-platform frameworks — encoding assets, debugging API contracts, generating deep link QR codes, validating push notification payloads, and testing device-specific edge cases. These Tools.Fun utilities handle the browser-based tasks that come up constantly during mobile development, without requiring a simulator, device, or build cycle to run.

Part of the Tools for Developers series. See the hub article for the complete guide.

Base64 Encoder / Decoder

Encode small images, icons, and binary assets to Base64 for embedding directly in JSON API responses, avoiding extra image download requests for tiny assets. Decode Base64-encoded images in API responses to preview them without writing decode code in your app first.

Push notifications: APNs and FCM payloads sometimes contain Base64-encoded images or authentication tokens. Decode them here to inspect the content during debugging.

JSON Formatter & Validator

Format and validate JSON API responses, push notification payloads (APNs, FCM), deep link configuration files (apple-app-site-association, assetlinks.json), and app configuration files. Spot malformed JSON before it causes a parsing crash in your app.

Universal Links: your apple-app-site-association file must be valid JSON served with Content-Type: application/json. Paste it here to validate before publishing — Apple's CDN caches it aggressively.

QR Code Generator

Generate QR codes that encode deep links for testing Universal Links (iOS) and App Links (Android) without needing to send yourself a text message. Create QR codes for app store links, in-app navigation routes, onboarding invite codes, and printed marketing materials pointing to app downloads.

Deep link testing: encode your deep link URL (myapp://path/to/screen) as a QR code, scan it with your device's camera app, and verify the OS routes it to your app correctly.

URL Encoder / Decoder

Encode special characters in deep link URLs, custom URL scheme parameters, and Universal Link paths. Decode percent-encoded URLs from analytics events, push notification click tracking, and URL routing logs to understand where users are navigating.

URL scheme tip: if your deep link passes data as query parameters (e.g. user names, email addresses), always URL-encode the values — special characters break URL parsing in both iOS and Android.

Timestamp Converter

Convert Unix timestamps from API responses, local database records, and push notification delivery reports to human-readable dates. Verify TTL values in push notification scheduling and debug time-sensitive features like countdown timers, session expiry, and limited-time offers.

Color Converter

Convert brand colours between HEX and RGB values for use in iOS (UIColor(red:green:blue:alpha:)), Android (Color.parseColor()), and cross-platform frameworks (Flutter, React Native). Ensures consistent colour rendering across platforms when translating design specs.

React Native: RN only accepts HEX or named colours in StyleSheet. Convert your RGB values here before dropping them into your stylesheet.

Code Diff Tool

Compare two versions of an API response, configuration file, or app manifest side by side. Useful for reviewing changes between API versions during app update planning, comparing feature flag configs, and auditing Info.plist or AndroidManifest.xml changes.

RegExp Tester

Build and test regular expressions for client-side input validation: phone number formats, postal codes, email patterns, and username constraints. Test against representative inputs across different locales before shipping validation logic.

Character Counter

Count characters in push notification titles and bodies to stay within platform limits: APNs limits the payload to 4 KB total; FCM notification titles are typically capped at ~65 characters for reliable display across Android devices. Also verify App Store description field lengths.

Push notification limits: iOS notification title: ~50 chars. Body: ~110 chars before truncation on the lock screen. Test your copy here before shipping notification templates.

JSON to YAML Converter

Convert JSON configuration files to YAML for CI/CD pipelines (Fastlane, Bitrise, Codemagic), Kubernetes-based mobile build infrastructure, and cross-platform framework configuration files that prefer YAML format.

Hash Generator

Generate SHA-256 checksums to verify the integrity of downloaded SDK packages, binary frameworks, and app assets. Compare checksums against published values to confirm you haven't received a tampered file.

Password Generator

Generate strong random strings for keychain-stored secrets, app-specific passwords, OAuth client secrets, push notification signing keys, and test account credentials used in automated UI test suites.

AES Encryptor

Test AES-256 encryption for local data storage security, offline cache encryption, and sensitive preference storage. Verify that your encryption and decryption implementations handle the same key and IV consistently before shipping data-at-rest protection.

Hex Converter

Convert hexadecimal device token values (APNs device tokens are 64-character hex strings) between formats for push notification registration, debugging APNS token mismatch issues, and working with raw binary data in Bluetooth LE characteristic values.

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