Independent mobile studio

Mobile software that leaves you in control.

Bullet Tech builds native Android and iOS apps around a simple rule: the useful part should run on your device, and the data it produces should stay somewhere you hold the key to. Our work is open source, so the claim is checkable rather than promised.

See our apps Browse the code ↗

Kotlin Multiplatform Jetpack Compose SwiftUI Rust core libraries Open source

Our apps

Two products, one principle

Both ship for phones and tablets, both keep their state on hardware or infrastructure the person using them owns.

Loopky

Learn anything, remember everything

Android & iOS

A flashcards app that fuses TinyCards' playfulness, Anki's spaced repetition, and Pubky's decentralized identity and social graph. Study queues are scheduled for you; the grade buttons tell you the interval before you press them.

There is no Loopky account and no Loopky server. You sign in with a key held by Pubky Ring, and your decks and study progress are written to a Pubky homeserver you hold the key to. Built with Kotlin Multiplatform, with native SwiftUI screens on iOS and real two-pane layouts on tablets.

Spaced repetition
Paste-to-import decks
Pubky identity
Deck discovery
Tablet layouts

Source on GitHub ↗ Privacy policy ↗

Loopky Today screen showing the daily study queue — Today

Loopky study screen showing a card prompt — Study

Loopky Discover screen showing decks and tags — Discover

Mandacaru 🌵

Your mobile Bitcoin node

Android

A lightweight Bitcoin validator node that runs on your phone, powered by Utreexo and Floresta. Utreexo's accumulator replaces the full UTXO set with a compact proof, which brings storage down from tens of gigabytes to something a handset can carry — so the validating is yours, not a server's.

It ships a block and transaction explorer, raw transaction broadcast, peer controls, and a built-in Electrum server you can pair your own wallet with. Mainnet, Testnet, Testnet4, Signet and Regtest, in a Material 3 interface with light and dark themes.

Utreexo
Floresta
Electrum server
Block explorer
Multi-network

Source on GitHub ↗ Report an issue ↗

Mandacaru node screen showing sync status — Node

Mandacaru transactions screen — Transactions

Mandacaru blockchain explorer screen — Blockchain

About

Who is behind Bullet Tech

Bullet Tech is the independent studio of João Victor Sena, a mobile developer working on Android, iOS and Kotlin Multiplatform. It exists to ship a small number of apps properly rather than many quickly.

Privacy by architecture

We prefer designs where there is no central database to leak: keys on the device, state on infrastructure the user controls, no accounts to create.

Open by default

Our apps are developed in public on GitHub. Anyone can read what the app actually does instead of taking a marketing page's word for it.

Native craft

Jetpack Compose on Android, SwiftUI on iOS, shared logic in Kotlin Multiplatform and Rust. Adaptive layouts for phones and tablets, not stretched columns.

Privacy

What we collect

Bullet Tech does not operate accounts, profiles or analytics backends for the apps listed on this page, and this website itself sets no cookies and embeds no trackers. Each app states its own data handling in full; those statements are the authoritative policies.

Loopky

No Loopky account and no Loopky server. Your identity is a key you hold in Pubky Ring, and decks and study progress are written to a Pubky homeserver of your choosing. Read the full policy ↗

Mandacaru

The node runs on your device. It talks to the Bitcoin peer-to-peer network to sync and validate blocks, and any wallet descriptors you load stay local to the phone. See the project README ↗

Contact

Get in touch

Support requests, bug reports and feature ideas all go through GitHub, where they stay public and trackable.

Open an issue on the repository of the app you are using, or reach the studio through its GitHub profile.

GitHub profile ↗ Loopky issues ↗ Mandacaru issues ↗