Bitcoin transactions are public, which can let observers connect addresses to real people. In 2013, developer Gregory Maxwell proposed CoinJoin, a method where multiple users combine inputs and outputs into one transaction to make it harder to tell who paid whom. This idea became a foundation for later wallet tools that offered transaction privacy without changing Bitcoin’s base rules.
In late 2013, Blockchain.info began offering SharedCoin, an implementation of CoinJoin aimed at improving user privacy. It packaged many users’ transactions into a single combined transaction, reducing direct linkability between inputs and outputs. SharedCoin helped bring CoinJoin from concept into mainstream wallet usage.
In 2014, security research showed that SharedCoin users could sometimes be identified using transaction analysis, especially against a determined investigator. The episode highlighted a key lesson: CoinJoin improves privacy, but design details and user behavior still matter. It pushed the community toward more careful threat models and more robust implementations.
In 2015, BIP47 described “reusable payment codes,” a way to share a single public identifier while still receiving payments to fresh addresses. This aimed to reduce the privacy harm of address reuse (when the same address is used repeatedly and becomes easy to track). Although not widely adopted across all wallets, BIP47 influenced later privacy discussions and wallet features.
In late 2015, developers created BIP141 (SegWit), which changed Bitcoin’s transaction format to separate signature (“witness”) data. One major benefit was reducing transaction malleability, a problem that could make it harder to reliably track unconfirmed transactions and build higher-level protocols. SegWit later became important for more advanced privacy and scaling tools.
In 2017, the SegWit upgrade activated on Bitcoin, enabling new transaction types and improving reliability for systems built on top of Bitcoin. By making certain transaction identifiers more stable and by introducing a new witness structure, SegWit opened the door to more efficient scripting and later upgrades. This also mattered for privacy tooling, since many wallets and protocols moved to SegWit-based designs over time.
Wasabi Wallet launched in 2018 as a privacy-focused Bitcoin wallet that made CoinJoin more accessible to everyday users. It paired a wallet interface with a centrally coordinated CoinJoin service, aiming to improve “fungibility” (the idea that each bitcoin should be interchangeable). Wasabi’s popularity helped make CoinJoin a widely discussed privacy option in the Bitcoin ecosystem.
In 2019, Bitcoin Core 0.19.0.1 introduced support for creating BIP158 compact block filters locally (via indexing) and also disabled certain older privacy-weak features (notably BIP37 bloom filters) by default. Compact block filters are designed so lightweight wallets can learn about relevant blocks with less information leakage to peers. This shift supported a broader move toward more private wallet synchronization methods.
In 2020, Wasabi developers described plans for WabiSabi, a new CoinJoin protocol intended to support variable output amounts while limiting what the coordinator can learn. Earlier CoinJoin designs often used equal-sized outputs to improve privacy, but that could make the tool harder to use. WabiSabi aimed to improve usability and privacy properties at the same time.
In 2021, Bitcoin activated Taproot, bringing Schnorr signatures and new scripting rules. This upgrade can improve privacy by making certain complex spending conditions look more like simple spends on-chain, reducing “transaction fingerprinting.” Taproot did not make Bitcoin anonymous, but it expanded the toolkit for building privacy-enhancing smart-contract patterns.
In 2022, Wasabi released a 2.0 testnet version, allowing users and developers to trial the redesigned CoinJoin system before main release. Testnet rollout mattered because privacy tools can fail in subtle ways, and broad testing helps find issues early. This step marked a transition from the original Wasabi coordinator design toward WabiSabi-based CoinJoins.
On June 15, 2022, Wasabi Wallet 2.0 launched, integrating WabiSabi and making CoinJoin more automated for users. The update focused on usability (less manual coin selection) while aiming to preserve privacy against blockchain observers and reduce what the coordinator can infer. This represented a major milestone in consumer-facing Bitcoin privacy tooling during the 2013–2023 period.
By 2023, CoinJoin had become a well-known Bitcoin privacy strategy, but it was also increasingly discussed in the context of compliance and law-enforcement scrutiny. This period highlighted a long-running tension: tools that improve everyday financial privacy can also be misused, shaping how services are offered and how wallets design defaults. The overall outcome by 2023 was a more advanced—but more contested—privacy toolkit built on CoinJoin and protocol upgrades like SegWit and Taproot.
Privacy tooling for Bitcoin: CoinJoin, Wasabi, and protocol privacy improvements (2013–2023)