SRC-20 is a token standard on the Bitcoin blockchain that governs the creation and management of fungible tokens via the Bitcoin Stamps protocol. Built on embedding data directly into Bitcoin transactions, SRC-20 tokens are designed for permanent, tamper-resistant on-chain storage. The standard draws parallels to Ethereum's ERC-20 but operates entirely within the Bitcoin network, with all transaction fees paid in BTC.
SRC-20 was introduced in March 2023 by a developer known as Mike In Space, emerging alongside a wave of Bitcoin-native protocols following the rise of Bitcoin Ordinals and the BRC-20 token standard. The project's name, Bitcoin Stamps, is an acronym for Bitcoin Secure Tradeable Art Maintained Permanently, reflecting its original purpose of enabling immutable on-chain storage of digital artwork.
The protocol traces roots to Counterparty, a peer-to-peer platform built on Bitcoin in 2014 that allowed users to burn BTC in exchange for the native XCP coin to execute smart contracts and issue tokens. Early Bitcoin Stamps used the Counterparty API to broadcast data to the blockchain. Starting from Bitcoin block 796,000, SRC-20 transactions were encoded directly on the Bitcoin blockchain, removing dependency on Counterparty and making the process self-contained.
Bitcoin Stamps work by converting an image file into a base64-encoded string. The encoding attaches the prefix "STAMP:" to the string and places it in the description key of a Bitcoin transaction. The transaction is then broadcast across the Bitcoin network, where nodes validate it and recompile the data into its original form. Transactions without a valid "STAMP:base64" string in the description key are not recognized as legitimate Stamps and are excluded from the Bitcoin Stamps Protocol index and API.
This approach is technically distinct because of where the data lands. Instead of being written into witness data or off-chain storage, Stamp data is embedded directly into Bitcoin's Unspent Transaction Output (UTXO) set using Pay-to-Script-Hash (P2SH) transactions. UTXOs are discrete units of cryptocurrency generated and held as outputs of prior transactions. Full nodes must maintain the UTXO set to verify new transactions, so data stored there cannot be pruned or selectively removed. This gives SRC-20 tokens a permanence other inscription-based approaches on Bitcoin do not guarantee.
SRC-20 tokens support image files in JPG, GIF, PNG, and SVG formats. The recommended resolution is 24x24 pixels, though creators can encode higher-resolution files at the cost of higher transaction fees. The standard also inherits a multi-signatory structure from the Stamps protocol, which applies whether transactions are broadcast through Counterparty or directly on-chain.
SRC-20 is frequently compared to two other token standards: BRC-20 on Bitcoin and ERC-20 on Ethereum.
BRC-20 tokens rely on the Bitcoin Ordinals protocol and store data in the witness field of a Bitcoin transaction block. Witness data is subject to pruning by nodes, so BRC-20 token data could be removed from some nodes over time. BRC-20 enforces stricter data size limits, producing more predictable and typically lower transaction fees. These size constraints, combined with Segregated Witness discounts, make BRC-20 transactions cheaper to execute. SRC-20 tokens, by contrast, offer flexible data sizing at the cost of potentially higher fees for larger payloads. Additionally, BRC-20 has broader exchange and wallet support, while SRC-20 remains in earlier ecosystem stages.
ERC-20 serves as a more distant but conceptually relevant comparison. On Ethereum, ERC-20 defines a standardized interface for fungible tokens that has become the foundation for decentralized finance, stablecoins, and governance tokens across the Ethereum ecosystem. SRC-20 mirrors that ambition on Bitcoin, extending the network's utility beyond simple value transfer without requiring modifications to Bitcoin's core protocol.
To create or interact with SRC-20 tokens, users typically use wallets and tools built for the Stamps ecosystem. The Stamp Wallet browser extension for Chrome supports minting, deploying, and transferring SRC-20 tokens. Rarestamp is another platform supporting token deployment. Once a Stamp is decoded, the image data is uploaded to Stampchain.io, where it becomes accessible and tradeable. OpenStamp and Stampscan are the main platforms for exploring and trading SRC-20 tokens. Stampscan also functions as a token tracker for supply, holder counts, and market data.
Prominent SRC-20 tokens include STAMP, BITDN, and KEVIN. STAMP, which names the broader technology, has more than 4,300 valid holders. Since launch, the cumulative market capitalization of top SRC-20 tokens has exceeded $100 million, with STAMP contributing a significant share. These numbers reflect growth of a niche but active community around the standard.
Looking ahead, the SRC-20 standard is discussed as a potential building block for broader decentralized finance applications on Bitcoin, including lending protocols, staking, and asset tokenization. As of this writing, such protocols have not yet been built for SRC-20 tokens, though their development is a stated community goal.
SRC-20 tokens have attracted skepticism from parts of the Bitcoin community that view the storage of non-financial data on-chain as unnecessary congestion. Critics argue that embedding image data in UTXOs inflates the size of a set that all full nodes must maintain, adding overhead without contributing to Bitcoin's core function as a payment network. Bitcoin commentator Junseth has described SRC-20 tokens as functionally similar to Ordinals, characterizing the distinction as merely a different accounting system. Supporters, including the protocol's creator, counter that UTXO-based storage confers genuine immutability benefits that witness-based approaches cannot match.
Scalability is a further constraint. Bitcoin's block size and the cost of on-chain transactions place practical limits on how much data can be stored and at what expense. As the ecosystem grows, higher demand for UTXO-based inscriptions can drive up fees for all Bitcoin users, not just those interacting with Stamps.
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