Presented by the President of Bitcoin Unlimited at the Blockchain Futurist Conference 2025, Toronto, Canada
Approximately 3,000 kilometers northwest of here lies the Burgess Shale, an extraordinary geological formation that serves as evidence of a period of intensified Darwinian natural selection. Fossils of soft-bodied organisms, preserved within its strata, display astonishing and diverse body plans, features that seem drawn from science fiction. Eyes on stalks, dorsal spikes, horns spanning an entire body, any adaptation that could evolve and confer even a slight advantage was tried, developed, and tested in open competition.
Epoch of Cryptocurrencies
Today, we are witnessing a parallel epoch of Darwinian natural selection, on steroids, within the world of cryptocurrencies. Here, any imaginable feature conceived by developers and researchers is implemented in code and released into the wild to compete for users, adoption, and ultimately, value. In this context, success is measured not by price, but by market capitalization. The larger the market cap, the more dominant the cryptocurrency becomes. And this is no trivial metric, the combined market capitalization of cryptocurrencies now lies in the trillions of dollars and is on track to surpass that of gold within the coming decade.
Sixteen and a half years have passed since Satoshi Nakamoto launched Bitcoin. In that time, enormous resources, both financial and intellectual, have been directed at creating new features across an expanding landscape of digital assets. Meanwhile, Bitcoin itself has largely focused on security hardening and conservative refinements. If Bitcoin were launched today, with its 10-minute block intervals and lack of token or DeFi support, it would likely be ignored. Users are not concerned with what lies beneath the surface. They want products that work. A seamless, rewarding user experience (UX) drives retention, adoption, and investment. And that, in turn, increases market capitalization, solidifying dominance in a borderless global economy.
What users expect is simple to list but hard to deliver: autonomy, reliability, security, minimal fees, privacy, speed, flexibility, and broad accessibility. Meeting these demands requires ambition from the designers, developers, and architects of cryptocurrency infrastructure. Finance in the 21st century is vastly more complex than it was fifty years ago. Despite 16 years of progress and over 10,000 exchange-traded cryptos, none fully deliver on all the attributes users require, and that brings us to Nexa.
Introducing Nexa
Nexa is a UTXO-architecture cryptocurrency, based on the original design by Satoshi Nakamoto, including a four-year mining reward halving cycle. It was fairly launched by the Bitcoin Unlimited team, who are now entering their tenth year of cryptocurrency development. However, the similarities to Bitcoin end there. Nexa’s codebase is rigorously optimized for parallel processing. Its currency unit, NEX, is denominated with two decimal places, a format more familiar to the global public. The current proof-of-work model incorporates partial Schnorr signature generation, with a hard fork scheduled for Q1 2026 to implement full blinded signature generation, rendering block withholding attacks infeasible.
The scripting language used by UTXO-based cryptocurrencies, including Bitcoin, Litecoin, and Nexa, was originally designed to be limited, ensuring deterministic execution. This design choice, analogous to the mechanics of a vending machine, was made by Satoshi to prioritize security and simplicity over flexibility. Yet the Bitcoin Unlimited development team has taken this scripting model to the edge of what is possible in terms of smart contract functionality. While Nexa scripting remains effectively non-Turing complete for blockchain validation purposes, its expressiveness makes it arguably Turing complete during transaction construction. Nexa introduces a high-level language, NEX Script, which allows for easier creation and testing of complex transactions. This empowers developers while maintaining the efficiency and determinism required for scalable execution.
UTXO vs. Account-Based Models
The UTXO set represents the global state of funds, while the blockchain serves to prove its validity. A user may control one or more wallets with multiple UTXOs, and their aggregate value forms the balance. Satoshi’s decision to avoid an account-based model was profoundly wise; it created a system that is simple, efficient, and scalable, attributes that Nexa preserves.
Turing-complete languages, like Solidity in Ethereum’s account-based model, create unpredictability. Because the impact of a transaction cannot be known at verification time, transactions must be processed sequentially, limiting scalability. In contrast, UTXO systems allow for massive parallelization, enabling Nexa to handle thousands of transactions concurrently via multi-threaded processing.
Tokens and Smart Assets
Tokens are fundamental to the 21st-century economy. Consider the widespread adoption of USDT across Ethereum, Tron, and other chains. It provides a stable, convenient medium of exchange, without needing its own blockchain. Nexa boasts the most advanced token support of any UTXO chain, and arguably any account-based one. Tokens are natively integrated into the base layer, miner-validated, and retain all the benefits of the main NEX unit. Nexa supports non-fungible tokens (NFTs) with commitment hashes embedded in the UTXO set. Platforms like Nifty Art and Nebula enable users to upload, view, and trade NFTs, including private NFTs. Additional innovations, such as atomic secret exchange, are under active development.
Lessons from the Lost Decade
Bitcoin and Ethereum have each suffered from what can be described as a “lost decade”. In Ethereum’s case, the complexity of Solidity has led to increasingly burdensome Layer 2 solutions. Even Vitalik Buterin has recently suggested that Ethereum must strive for simplicity akin to Bitcoin. Meanwhile, Bitcoin has clung to ideological rigidity, resisting hard fork upgrades and rejecting native support for scalability, tokens, and DeFi.
Cryptocurrency holds the promise of combining the scarcity of gold with the flexibility of digital cash. But to fulfill this, it must handle the scale of modern financial systems. With approximately 5 billion fiat transactions occurring daily, over 60,000 per second, cryptocurrencies must rise to meet or exceed this threshold. Nexa already demonstrates the capability to scale. Testing on its development network has shown throughput of 20,000, 40,000, and up to 60,000 transactions per second, utilizing over 9,000 threads on a 16-core server, with nodes in Italy and Canada using standard ISP connections.
Innovations in Hardware and Privacy
Nexa introduces “improving”, an innovation that allows nodes to prune blockchain history more efficiently by implementing minor commitments to the UTXO set in 2026. In hardware, Nexa is pioneering Blitz—an FPGA accelerator card that verifies Schnorr signatures (the most intensive part of transaction validation) using minimal energy. The current prototype performs 30,000 elliptic curve signature verifications per second, running on a chip the size of a cigarette packet. For privacy and coordination, CapD offers a decentralized, anonymous messaging service. Users can exchange partial transactions peer-to-peer, using proof-of-work to deter spam. CapD enables coordinated trades and smart contract execution without centralized servers.
Preparing for Quantum Threats
Quantum computing represents an existential threat to current cryptographic systems. Four principal types of public keys are exposed, notably in Bitcoin’s early mining rewards and Taproot-enabled keys. Once a crypto amount is spent, the associated public key becomes visible, opening a vulnerability window, especially for transactions lingering in the mempool. Surveys of experts predict cryptographic compromise from 2035 to 2040, with conservative estimates extending to 2055–2060. Yet even a 5% probability within a decade demands urgent mitigation. In response, Nexa has an active program to implement post-quantum cryptographic support across its wallets and hardware infrastructure. This early adoption approach ensures users have adequate time to migrate assets securely.
Conclusion
Bitcoin Unlimited brings to Nexa a decade of expertise and an unwavering commitment to competitive development. We are determined to give Nexa every advantage in the race for global usage and adoption.