Convex Programmer's Calculator vs ChipVault

Easily convert between hexadecimal, decimal, octal, and binary. Calculate the two's complement of any number. Flip a number's bytes to switch its endianness. Bit-shift left and right. Bit indicators and word grouping make binary easier to read. Tap the number to copy, paste, and clear. Swipe left or right on the number to backspace.

The only iOS app dedicated to NXP DESFire EV2 and EV3 NFC cards. ChipVault turns your DESFire cards into hardware-backed personal data vaults — AES-128 encrypted at the chip level, secured by your own master password. No cloud, no servers, no accounts, no subscriptions. The cards in your wallet are the storage. SECURE FIRST. Traditional NXP card tools fall short on security when working with these chips. ChipVault treats native AES encryption, EV2 Secure Messaging, and proper key derivation as first-class citizens — not afterthoughts. Every byte written to a card is encrypted with a key derived from your master password and that card's unique UID. The same data on a different card is a different ciphertext. A different password unlocks nothing. The chip enforces this at the silicon level. WHAT YOU CAN DO — Personalize a blank DESFire EV2 or EV3 card into a ChipVault: pick up to 8 categories from a palette of 15+ pre-canned options (Financial, Medical, Travel, Auto, Insurance, Tools, Credentials, Licenses, Subscriptions, Crypto Recovery, Family, Work, Notes, Wi-Fi & IoT, Personal IDs) or roll your own with custom names — Store passwords, codes, account numbers, notes, recovery phrases — each entry is a simple key plus a multi-line value, with optional hide-by-default for sensitive fields — Read your data with a tap and your master password — Edit a card after enrollment: rename it, change its theme and icon, rename any category — all instant, no NFC tap needed — Add new categories or delete existing ones on a card you've already personalized — one NFC tap each, with confirmation — Clone an entire card to a backup card — your safety net stays in your physical control, with per-trait toggles for what carries over (name, theme, icon) — Recover from a stuck chip memory allocator with Reset & Restructure — wipes entries and rebuilds the card with your current category set (chip-level recovery you'll rarely need, but you'll be glad it's there if you do) — See exactly how much space each category is using with the visual storage donut — Reset any card back to factory state with a single command — Delete individual entries cleanly with no leftover ghost data USE CASES — A password manager backup that doesn't live on anyone's cloud — A travel-only vault you carry separately from your phone — Encrypted storage for crypto recovery phrases that survives device loss — An emergency credentials kit that goes in a safe deposit box — A shared medical info card a family member can read with their own ChipVault install (if they know your master password) PRIVACY BY DESIGN ChipVault has no servers. No analytics. No tracking SDKs. No accounts to create. Nothing you do leaves your device, except a small operational record stored in your own iOS Keychain (which you control). Your master password is never transmitted, never logged, and never recoverable — write it down somewhere safe. WHAT YOU'LL NEED — An iPhone with NFC support (iPhone 7 or later) — One or more NXP DESFire EV2 or EV3 NFC cards (widely available online — see the in-app guide) ONE-TIME PURCHASE A 20-day free trial. After that, a single one-time purchase unlocks ChipVault forever — on all your devices. No subscriptions. Ever. ABOUT N0AGI ChipVault is built by N0AGI LLC, an indie shop focused on tools that respect your data and your wallet. Questions, feedback, or bug reports: n0agi@n0agi.com