Ordinals/BRC-20 Marketplace Development

When Bitcoin Ordinals burst onto the scene, developers faced the challenge of trading assets without smart contracts. We solved it through atomic PSBT swaps. Initially, the trading volume of Ordinals exceeded $1.5 billion, and the Bitcoin network was several times congested due to inscription transactions. Magic Eden, Ordinals Wallet, Gamma.io — marketplaces arrived quickly, but the development stack is fundamentally different compared to EVM: no smart contracts, no native escrow, transactions are atomic via PSBT mechanics. If you need a Bitcoin NFT marketplace, contact us for a consultation.

Protocols: Ordinals, BRC-20, and Runes

Ordinals — Inscriptions on Bitcoin

The Ordinals protocol introduces the concept of ordinal numbers for satoshis. Each satoshi is numbered in mining order. An inscription attaches data to a specific satoshi through Bitcoin Script witness data. The data is stored on-chain in Bitcoin — this distinguishes Ordinals from NFTs on Ethereum, where metadata is typically on IPFS.

Technically: an inscription is created via a commit-reveal transaction. The commit transaction creates a P2TR output with Tapscript containing the data. The reveal transaction spends this output, publishing the data in the witness. After that, this satoshi carries the inscription and can be transferred like an NFT.

For a marketplace, critical aspects include: parsing inscription metadata (JSON, image/png, image/webp, text/plain), determining the Ordinal sat range in a UTXO, and tracking ownership through Bitcoin addresses.

BRC-20 — Tokens on Top of Ordinals

BRC-20 is an experimental token standard based on Ordinals. Operations are encoded in JSON inscriptions:

{ "p": "brc-20", "op": "deploy", "tick": "ordi", "max": "21000000", "lim": "1000" }
{ "p": "brc-20", "op": "mint", "tick": "ordi", "amt": "1000" }
{ "p": "brc-20", "op": "transfer", "tick": "ordi", "amt": "500" }

It's important to understand: BRC-20 balances are not stored on an address like ERC-20. A balance is the sum of unspent transfer inscriptions associated with an address. For trading on a marketplace, an indexer — a service that reads the entire Bitcoin history and builds current balances for each address — is required. When developing a BRC-20 marketplace, the indexer is key.

Runes — The Next Generation

The Runes protocol is a more efficient alternative to BRC-20. It uses OP_RETURN output instead of witness data, which is cheaper. Balances are stored in the UTXO model, closer to native Bitcoin. Runes already have several marketplaces, but the ecosystem is younger than BRC-20. If you are considering a Runes marketplace, we can also offer integration of this protocol.

Protocol Comparison

How Atomic Swaps Work Without Smart Contracts?

The main difference from EVM marketplaces: there is no smart contract as escrow. Bitcoin does not support arbitrary code. Swaps are done via PSBT (Partially Signed Bitcoin Transaction). Learn more about PSBT in Wikipedia.

Listing and purchase scheme:

1. Seller creates PSBT: Input — UTXO with Ordinal, Output — seller's address + requested price in BTC. Seller only signs their input with the SIGHASH_SINGLE | SIGHASH_ANYONECANPAY flag.
2. PSBT is published to the marketplace. The marketplace stores this as a listing.
3. Buyer supplements the PSBT: adds their inputs (BTC for payment) and an output to their address (receiving the Ordinal). Signs with their keys.
4. Transaction broadcast: atomic — either seller gets BTC and buyer gets the Ordinal, or nothing.

SIGHASH_ANYONECANPAY allows the seller to sign a partial transaction that anyone can add inputs to. This is atomicity without a smart contract. This mechanism underlies the atomic Bitcoin swap.

Implementation uses libraries: bitcoinjs-lib (JavaScript), rust-bitcoin (Rust). PSBT construction and validation are critical; an error here means loss of NFT or BTC.

Why Is the Indexer Critical for Liquidity?

The indexer is the most complex component. It must:

1. Read the entire Bitcoin blockchain from genesis (or from the block of Ordinals appearance).
2. Parse all inscription transactions, build a mapping satoshi → inscription data.
3. Track ownership: which Bitcoin address is associated with each Ordinal right now.
4. For BRC-20: parse JSON operations, calculate balances for addresses.
5. Stay synchronized with new blocks in real-time (latency no more than 10 seconds).

Open-source solutions:

• ord (original indexer by Casey Rodarmor, Rust) — reference implementation.
• hiro-systems/ordhook — more performant, supports webhooks.
• unisat/ord-utils — JavaScript library on top of the ord indexer.

For a marketplace from scratch: we run an ord node + Bitcoin full node, and build our own API with caching in PostgreSQL or Redis. Synchronization from zero takes up to 5 days.

Using a ready-made ordinal indexer reduces development time.

Wallet Integration

Bitcoin wallets supporting Ordinals:

• Unisat Wallet — the most popular, browser extension, supports PSBT signing.
• Xverse — mobile + extension, supports BRC-20 and Ordinals.
• Leather (hiro.so) — stack from Hiro Systems, good documentation.
• OKX Wallet — largest by user count in Asia.

Standard for wallet interaction: Unisat provider API (de facto standard for Ordinals). Analogous to window.ethereum, but window.unisat. Methods: requestAccounts(), signPsbt(), pushPsbt().

const accounts = await window.unisat.requestAccounts()
const signedPsbt = await window.unisat.signPsbt(psbtHex, {
  autoFinalized: false,
  toSignInputs: [{ index: 0, address: sellerAddress }]
})

For multi-wallet support — sats-connect library, analogous to WalletConnect for Bitcoin. We provide Unisat wallet integration and support for other popular wallets.

Typical Implementation Problems

What's Included in the Work

• Detailed documentation: PSBT transaction scheme, indexer description, wallet OAuth schemes.
• Source code on GitHub with CI/CD and tests (90%+ coverage).
• Access to admin panel with transaction monitoring.
• Deployment instructions for your own servers.
• Consulting support for 30 days after launch.

Development Process

Infrastructure (1 week). Bitcoin full node + ord indexer, blockchain synchronization, listing database.

Backend API (2 weeks). REST API: collections, listings, search, activity. PSBT service for generating and validating swaps. WebSocket for real-time updates.

Frontend (2–3 weeks). Next.js + TypeScript, multi-wallet support (Unisat, Xverse, Leather), inscription gallery, trading interface, BRC-20 balances.

Testing (1 week). Testnet (signet) + regtest environment, end-to-end testing of PSBT swaps.

Timeline Estimates

MVP marketplace for Ordinals with basic listing and PSBT swaps — from 4 to 6 weeks. Full marketplace with BRC-20, Runes, indexer, and multi-wallet — 2–3 months. The cost is determined after discussing the set of supported protocols and indexer requirements. Our blockchain development experience exceeds 7 years, and we have delivered over 70 projects, including NFT platforms on various networks. We guarantee source code transparency and post-launch support. Contact us to order a turnkey Bitcoin marketplace and get a consultation on architecture and timeline estimates.

Why does NFT marketplace development require a comprehensive approach?

We see that at first glance, an NFT contract looks simple: ERC-721, mint(), IPFS for metadata — that's it. In practice, it's this 'simplicity' that hides most problems — from bots buying out the entire mint in the first block to broken royalties on the secondary market. We often hear: Make a collection like others in a week — and a month later it turns out gas has tripled due to an unoptimized for loop, or OpenSea cannot see metadata after reveal. We know each of these pitfalls and build processes to avoid them.

Over 5 years of working with blockchains, we have implemented 40+ NFT projects, including marketplaces with dynamic attributes and cross-chain bridges. We have accumulated a library of proven templates — some of which we break down below.

Which standard to choose: ERC-721 or ERC-1155?

ERC-721 — each token is unique, one owner. Suitable for collections where each NFT has individual attributes and a direct owner → tokenId mapping.
ERC-1155 — multi-token standard: one contract holds both fungible and non-fungible tokens. It uses balanceOf(address, tokenId) instead of ownerOf(tokenId). A single transaction can transfer multiple different tokens via safeBatchTransferFrom. This saves gas on bulk operations — important for game items, tickets, edition collections. ERC-1155 is 2–3× more gas-efficient than ERC-721 for batch transfers.

Specific case: a game project with 50 types of items, each with a supply of 10,000. ERC-721 — 500,000 unique tokens, huge overhead on mappings. ERC-1155 — 50 tokenIds, balanceOf per player. Gas per transfer is 2–3 times lower, contract deployment is cheaper. For such tasks, we use OpenZeppelin ERC-1155 with custom modifications.

Metadata: on-chain vs IPFS vs centralized

The standard route is tokenURI() returning a link to a JSON with fields name, description, image, attributes. Three storage options:

• Centralized server — cheapest and most flexible. Risk: server goes down, company closes — NFT loses metadata. Not suitable for collections claiming long-term value.
• IPFS + Pinning — content-addressed storage, the link is bound to the content hash. Pinata or NFT.Storage provide pinning. Important: IPFS does not guarantee availability by itself — an active pinning service is needed. If it shuts down, data may disappear if no one keeps a copy.
• On-chain metadata — base64-encoded SVG or JSON directly in tokenURI. Maximum reliability, but expensive: for a collection of 10,000 tokens, gas costs may exceed $5,000. Suitable for generative art projects where visuals are generated from on-chain attributes (Nouns, Loot).

For most collections, we choose IPFS with Pinata for images + on-chain attributes for traits — a good balance. We validate files against a JSON Schema before upload; a typical mistake is unescaped quotes, causing marketplaces to display a blank screen.

{
  "name": "Token #1",
  "description": "A unique NFT",
  "image": "ipfs://QmHash/image.png",
  "attributes": [{"trait_type": "Background", "value": "Red"}]
}

Dynamic NFT: metadata that changes

Dynamic NFT updates metadata in response to external events — match results, character levels, real-world data via Chainlink. Architecturally, it's a combination: the smart contract stores state → tokenURI() generates metadata from the state on-chain. Caching problem: OpenSea and other marketplaces aggressively cache. The standard invalidation mechanism is a MetadataUpdate(tokenId) event from ERC-4906. OpenSea listens to this event and clears the cache. Without it, updated metadata may not appear for weeks.

Chainlink Automation (formerly Keepers) for automatically updating state on the contract on a schedule or condition — a standard solution for dynamics.

How to protect mint from bots?

Allowlist via Merkle tree — standard. The list of addresses is hashed into a Merkle root, stored in the contract. During mint, the user provides a Merkle proof — the contract verifies without storing the full list. We use OpenZeppelin MerkleProof library.

Reveal mechanism — on mint, a placeholder is issued; real traits are revealed after the sale ends. Otherwise, bots can scan pending transactions and snipe rare traits via frontrunning. But reveal requires a commitment scheme — the random seed must be fixed before mint or use Chainlink VRF.

Chainlink VRF for fair randomization of traits. VRF request at mint → callback with verifiable random number → assign traits. This adds ~2 transactions and latency but guarantees fairness. Chainlink VRF v2.5.

Rate limiting — require(mintedPerWallet[msg.sender] < maxPerWallet). Does not protect against multi-wallets but raises attack cost. For premium projects, we often add proof-of-work directly in the contract (via EIP-2612 signatures).

Royalties: the real market state

ERC-2981 — on-chain royalty standard. The contract returns (recipient, amount) for any sale price via royaltyInfo(tokenId, salePrice). Marketplaces query this on each sale. Problem: adherence to royalties is voluntary for marketplaces. Blur launched with zero royalties, triggering a wave of other platforms. The situation has partially stabilized: OpenSea supports ERC-2981, Blur added optional ones. Royalty payments can represent 5–10% of secondary sale volume, so getting them right matters.

Attempts to enforce royalties on-chain by restricting transfers only to approved marketplaces (operator filtering) were proposed by OpenSea via OperatorFilterRegistry. This breaks composability — you cannot transfer an NFT through a custom contract. Most serious projects have abandoned this approach. For projects where royalties are critical, we build a custom marketplace within the ecosystem plus an incentive structure for users to trade there.

Lazy minting and gas-free mint

Gas-free mint via signature: the creator signs a voucher (tokenId, tokenURI, price, signature), the buyer provides the voucher in mint() — the contract verifies the signature via ECDSA.recover() and mints. Works on OpenSea via their Seaport protocol. Seaport is an optimized contract with minimal gas usage. Understanding its mechanics is important when integrating custom marketplace logic.

Stack for NFT projects

• Contracts: Solidity 0.8.x, OpenZeppelin ERC721Enumerable or ERC721A (Azuki) for gas-optimized batch mint, ERC1155 from OpenZeppelin
• VRF and automation: Chainlink VRF v2.5, Chainlink Automation
• Storage: Pinata (IPFS pinning), NFT.Storage, Arweave for permanent storage
• Marketplace: OpenSea Seaport protocol, custom integration
• Frontend: wagmi v2 + viem, RainbowKit for wallet connection, React + TypeScript

Development process

1. Mint mechanics design — allowlist, public sale, price curve (Dutch auction or fixed), limits per wallet
2. Contracts — with Foundry fuzz tests on mint limits, Merkle proof verification, royalty calculations
3. IPFS deployment — upload metadata and images before reveal, pin on at least two services
4. Reveal — if using Chainlink VRF, test on testnet mandatory: VRF subscription must be funded with LINK tokens
5. Marketplace integration — verify collection on OpenSea, configure royalties, test MetadataUpdate events
6. Deployment and monitoring — Tenderly for reentrancy detection, Etherscan API for contract verification, set up event alerts

Deliverables

• Source code of smart contracts (Solidity, Rust for Solana) with comments
• Test suite (Foundry/Hardhat) with ≥90% coverage
• Deployment documentation and integration instructions
• Access to pinning services (Pinata/Pinfluence)
• Metadata generation scripts (Python/JS)
• Support during marketplace verification
• 30 days of technical support after deployment

Timeline

Cost is calculated individually after auditing your task. Send a brief with your project description — we will provide a transparent estimate within 3 business days. For regular clients, there is a flexible discount system on batch orders. If you need a gas-optimized contract, order a free gas analysis. Get a consultation on marketplace architecture — leave a request, and we will evaluate your project in three days.