When building at the scale of OpenSea, speed and coverage are everything. Launching token trading across multiple chains could mean heavy indexing work and infrastructure management. Instead, OpenSea tapped into Zerion API to accelerate its go-to-market and unlock new possibilities for traders.
The Challenge: Multichain Token Data at Scale
As the world’s largest NFT marketplace, OpenSea already operates at a massive scale.
When OpenSea announced OS2, it wasn’t just a facelift, it was a rebuild from the ground up. The launch of OS2 brought NFTs and token trading together in one platform, expanded support for new chains, and introduced features like cross-chain purchases and real-time portfolio insights.
Expanding into ERC-20 token swaps put scale and development velocity into focus:
- Time to market — Indexing and normalizing token data across OpenSea’s 18+ chains supported at the time would require significant engineering effort.
- Scale requirements — Any solution needed to support tens of millions of requests daily while staying performant.
Launching OS2 meant evolving OpenSea into a truly multichain, multi-asset platform. This required solving speed, scale, and complexity simultaneously, which was a serious challenge even for the world’s largest NFT marketplace.
The Solution: Zerion API’s Wallet Positions Endpoint
To accelerate development, OpenSea integrated Zerion API’s Wallet Positions endpoint.
With a single call, Zerion’s endpoint returns all normalized token positions for any wallet across 26+ chains, including the 18 EVM networks supported by OpenSea. Balances are enriched with metadata and valued in USD, allowing developers to skip indexing entirely and focus on the product.
When selecting the API provider, several key advantages stood out for OpenSea:
- 18 chains covered from day one — Zerion supported all chains that OpenSea needed for the release, eliminating the need to integrate different solutions for different networks
- Normalized balances in one response — A single API call returned token balances for all supported chains
- Battle-tested infrastructure — Zerion already handled data at a consumer scale, both for its own products and for other API partners.
The Results: Shipping 3+ Months Faster, 467k DAU Supported
By integrating Zerion API for token trading in OS2 since day one, OpenSea unlocked:
- Faster time to market — The OpenSea team shipped token trading 3 months faster than an internal build, saving significant engineering resources and accelerating OS2’s roadmap.
- Full chain coverage with less complexity — All 18 supported chains integrated through a single API, cutting operational overhead.
- Reliability at scale — Zerion API served up to 467,322 daily active users of OS2, handling up to 1,000 requests per second.
With token trading live, OpenSea has now been able to deepen the trader experience. As the next step, OpenSea integrated Zerion API’s PnL endpoint to help traders understand their performance across chains and protocols. OpenSea’s estimated profit & loss shows the amount invested, realized, unrealized, and return.
“Zerion's API got us to market 3 months faster than an in-house build (an eternity in crypto) and with enough flex capacity to support 18 chains through switch-on of one of the largest rewards programs in the industry. We continue to see Zerion as a long-term partner in speed-to-market, and one of few providers in web3 today that offer APIs that scale to OpenSea's userbase.” — Chris Maddern, CTO at OpenSea
Build Like OpenSea
OpenSea’s OS2 launch included a serious challenge: unify token data across 18 chains, handling hundreds of millions of real-time requests. By integrating Zerion API’s Wallet Positions endpoint, OpenSea reduced engineering work and delivered a smooth trading experience while reducing infrastructure complexity.
Ready to ship faster? Get Zerion API keys and cut months off your time to market.