Open Source

Built by Blockstream. 100% open-source firmware and hardware. Unique 'Blind Oracle' PIN security model (no secrets stored on device when locked). Camera for air-gapped QR signing. Genuine Check hardware verification. Anti-Exfil protection against Dark Skippy attacks.

100% open-source (MIT license). No pre-built hardware to trust—build it yourself from generic components. Community-driven project since December 2020. Stateless design (no secrets stored on device). Reproducible builds for verification.

Opportunity Cost takes a refreshingly simple approach to Bitcoin education by meeting users exactly where they already spend time—browsing the web. The extension automatically detects prices across any website and displays their Bitcoin equivalent inline, eliminating the friction of constantly opening calculators or exchange apps. With support for 10+ fiat currencies, customizable display options (BTC or sats), dark mode, and per-site toggles, it delivers a polished experience that stays out of your way while fundamentally shifting how you perceive prices.

The privacy-first architecture is a standout feature. All price detection and conversion happens locally in your browser—no page content or personal identifiers are sent to remote servers. The only network request is fetching current BTC exchange rates, with no user data attached. Optional local statistics (like conversion counts) can be disabled or cleared anytime from the options page. Being fully open-source on GitHub, backed by established Bitcoin media outlet TFTC, and created by known Bitcoiners Marty Bent and Moses Finlay adds meaningful transparency. There's no account required, no ads, no subscription fees, and no monetization—just a free tool designed to help you think in sound money terms.

StartOS is fully open-source software built on Debian Linux, with all code available on GitHub for public audit. The system is designed around data sovereignty principles where Start9 has no access to user keys, passwords, or data—everything runs locally on hardware the user physically controls. Services communicate through Tor Hidden Services by default, providing encrypted, metadata-resistant connections without exposing home IP addresses.

The company has shipped hardware since 2020 and maintains an active development community with regular updates and a growing service marketplace. Their security approach includes neutralizing Intel Management Engine on supported hardware and running no trackers or telemetry. While at-rest encryption is currently basic with improvements planned, individual services like Vaultwarden add end-to-end encryption for sensitive data. All purchases include lifetime support and a two-year hardware warranty, demonstrating long-term commitment to customers.

SOC 2 Type II compliant. Powers Chipper Cash (50%+ BTC via Lightning).

BTC Map is a free, open-source project (AGPL-3.0 licensed) that does not custody any funds, process payments, or handle financial transactions. It functions purely as a mapping and discovery tool built on OpenStreetMap data, meaning there are no assets at risk and no financial trust required.

The platform operates with full transparency - all code is publicly available on GitHub with 53 stars, 20 forks, and 12 contributors. Privacy is prioritized with no cookies, no trackers, and GDPR-compliant analytics that delete data after 30 days. Geolocation processing happens client-side, so your location is never sent to BTC Map servers.

Data quality relies on a global community of volunteer contributors and "Shadowy Supertaggers" who verify merchant listings. The project has mapped over 18,000 merchants worldwide with more than 10,000 recently verified, and has earned integration into major Lightning wallets like Wallet of Satoshi as a trusted merchant discovery tool.

Pioneer in Bitcoin-paid microtasks. Pledged $180K to Brink for Bitcoin developer funding. Open-source Sphinx Chat. Non-KYC sats for workers.

Built by OpenSecret. Open-source server code. Secure enclaves with cryptographic attestation. Zero data retention. Listed in HRF AI for Individual Rights Toolkit.

Open-source. Integrated custodial Lightning wallet for easy onboarding. Nostr Wallet Connect (NWC) support for external wallets.

GNU AGPLv3 licensed. Fully browser-based—all data stored locally. No server dependency. Anonymous payments via Nostr and Lightning.

Built by ACINQ, creators of Eclair (one of the original Lightning implementations). Fully open-source. Runs a real Lightning node on your phone.

Fully open-source (AGPL). Embedded LND node option. No KYC. OLYMPUS LSP for 0-conf channels.

Fully open-source (MIT license). Built by Bull Bitcoin (founded 2013).

Open-source. Built on BDK (Bitcoin Dev Kit). OpenSats grant funded. No data collection.

Open-source. Native iOS app. Cashu protocol uses Chaumian blind signatures — mint can't see who sends or receives.

Originally Blockstream project, now by JAN3 (Samson Mow). Non-custodial. Uses Green Development Kit (GDK).

Founded 2017. Fully open-source (MIT license). Connect to your own Electrum server. No KYC.

Open-source. Web-based (no install needed). Uses Cashu protocol with Chaumian blind signatures for privacy.

Fully open-source (Apache 2). PSBT-native from the ground up. Supports all major hardware wallets. No data collection.

Created in 2011. Fully open-source (MIT license). One of the oldest and most trusted Bitcoin wallets. Private keys encrypted and never leave your computer. Decentralized server network.

Fully open-source. Built by Wizardsardine. Uses Miniscript for advanced recovery. Compatible with BitBox02, Coldcard, Ledger, Jade.

Fully open-source. Developed by Unchained Capital. Browser-based, runs locally. Stateless design — stores no data. BIP67 and BIP32 compliant.

Fully open-source. No ads, no tracking. Self-hostable. Integrated with 30+ wallets and services.

Built by Blockstream. Fully open-source (Esplora). Self-hostable. No tracking.

Fully open-source. Used by Namecheap ($73M+ in BTC revenue). Powers Bitcoin payments for thousands of merchants worldwide. No KYC, censorship-resistant.

Fully open-source. Maintained by industry-leading Bitcoin developers. Powers wallets like Cove, Envoy, and Mutiny. Funded by Spiral, OpenSats, and the BDK Foundation.

Fully open-source. Maintained by Spiral (Block). Powers apps like Mutiny Wallet and Cash App. Battle-tested in production.

Fully open-source. Implements BIP 78 (PayJoin V1) and BIP 77 (PayJoin V2). Funded by OpenSats and HRF.

Fully open-source. The most widely used Rust Bitcoin library. Foundation for BDK, LDK, and many other projects. Maintained by a dedicated team of Bitcoin developers.

Open-source SDK from Breez. Self-custodial by default with keys on user's device. Powers Lightning payments without requiring node management. Multiple implementations available (Spark and Liquid).

100% community-funded. Forked from Samourai Wallet source code (April 2024). GNU GPL v3 licensed. Tor integration with no DNS dependencies.

MIT licensed open-source. Backed by Jack Dorsey ($5M). Censorship-resistant decentralized social network.

Bitaxe is a fully open-source Bitcoin mining hardware project with no company or formal organization behind it—just a decentralized community of developers and contributors. Every aspect of the design is transparent: hardware schematics, PCB layouts, and firmware are publicly available for anyone to inspect, audit, or modify. This radical transparency means there are no hidden backdoors or proprietary code that users must blindly trust.

The project emerged from the Open Source Miners United (OSMU) community, which promotes decentralized, transparent mining hardware development. Because Bitaxe is mining hardware rather than a custodial service, it never holds your private keys or Bitcoin—your funds remain in your own wallet at all times. Security is determined by your own setup rather than trusting a third party with custody.

The community has demonstrated responsible security practices. When a CSRF vulnerability was discovered in early 2024 that could allow attackers on the same network to change mining pool settings, the maintainers quickly released a firmware patch and publicly communicated upgrade instructions. Build quality depends on your chosen vendor or your own assembly from open designs.

Bitcoin Keeper is a fully non-custodial, open-source wallet where users maintain complete control of their private keys. The company never has access to user funds and cannot sign or authorize transactions on behalf of users.

The application code is publicly available on GitHub (bithyve/bitcoin-keeper), allowing independent security review by the community. Bitcoin Keeper provides signed checksums and detached GPG signatures for APK verification, enabling users to confirm they are running authentic, unmodified software. WalletScrutiny has included Bitcoin Keeper in their build verification efforts, indicating attention to transparency.

The wallet supports connecting to your own Bitcoin node, eliminating reliance on third-party servers for transaction verification. Multi-key vault configurations distribute signing authority across multiple devices and locations, removing single points of failure. The app is Bitcoin-only, avoiding the complexity and attack surface of multi-asset wallets.

Bisq stands alone as a truly decentralized exchange where you never give up control of your bitcoin. Unlike centralized platforms that hold your funds and require identity verification, Bisq uses multisignature escrow so bitcoin only moves when both parties complete their obligations. All traffic routes through Tor, there's no central server to hack or subpoena, and no account to create means no personal data to leak. The entire system is open-source and governed by the Bisq DAO, where community members vote on fees, security deposits, and protocol changes using BSQ tokens.

The security model is elegant: both buyer and seller lock security deposits into multisig escrow, creating strong financial incentives to complete trades honestly. If disputes arise, they escalate through decentralized mediation and arbitration rather than corporate customer support. Trading fees run about 1.3% combined (0.15% maker, 1.15% taker) in BTC, or roughly half that when paying in BSQ tokens. While higher than centralized exchange fees, you're paying for genuine privacy and the elimination of counterparty risk. The newer Bisq Easy feature removes deposits and trading fees entirely for smaller trades under a few hundred dollars, using seller reputation instead of escrow.