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Frequently Asked Questions

General

What is Sera?

Sera is a stablecoin FX settlement layer that enables trading between stablecoins representing different fiat currencies (USD, EUR, GBP, SGD, JPY, and more). All settlement happens on Ethereum via open-source smart contracts.

What currencies are supported?

Sera supports many fiat currencies through various stablecoin issuers. See Supported Currency Pairs for the full list.

How do I get testnet tokens to try Sera?

Every stablecoin in the testnet token registry is mintable for free from the Sera testnet faucet on Sepolia: 0x4FAc3BB8B77547E2Da7ed903baDBeD2f46cBe65a. The easiest path is the "Get test tokens" flow in the web app at testnet.sera.cx; developers can also call the faucet contract directly with the token address they want. You will additionally need a small amount of Sepolia ETH for gas — grab some from any public Sepolia faucet.

Is Sera custodial?

Deposited assets are held in the Vault contract. Normal trading and instant withdrawal enforce signed instructions; privileged contract roles remain part of the trust model. Users can request delayed emergency withdrawal without the API. See Non-Custodial Design.

Trading

What order types are available?

Sera supports limit orders (specify your price), instant swaps (fill-or-kill at the best available price), and Virtual Liquidity batches (multi-pair orders with shared collateral). See Order Types and Virtual Liquidity for details.

What is Virtual Liquidity?

Virtual Liquidity (VL) lets you place 2 to 50 limit orders across distinct markets backed by a single shared budget. Query GET /config (under limits.vl_batch) for the current cap. Instead of locking collateral for each order independently, a VL batch freezes only the maximum of any single order's cost. When one sibling fills, the others are automatically resized to fit the remaining budget. Exact duplicates and inverse pairs count as the same market and are rejected. See Virtual Liquidity.

How do instant swaps work?

Instant swaps use Smart Order Routing (SOR) to find the best price across all available liquidity. The SOR engine routes through intermediate currencies when a direct path isn't optimal — for example, a JPY→GBP swap might route through USD if that produces a better rate.

  1. Request a quote via the API — the SOR engine finds the optimal route
  2. Sign the quote parameters with your wallet
  3. Submit the signature to execute

Swaps are atomic — they either execute in full or are rejected entirely. See Swap Trading.

What are the fees?

Settlement transactions consume EVM gas and are signed and broadcast by a relayer executor, whose wallet pays the chain fee. This does not require the limit-order owner to hold ETH merely for that settlement. User-visible fees are described by the quote and settlement_economics.fees_paid; this is not a promise that every deployment offers free trading. Transactions you send yourself, such as approve, deposit and withdrawal, require network gas. Swap execution gas is included in the quote; see Fees.

Can I cancel an order?

Yes, using a signed cancel request for an open or partially filled order. The server applies a configurable cooldown (default 300 seconds); the current implementation has no high-volume account exemption. A 429 can also be rate limiting. Inspect the response and query the final order/settlement state.

What happens to partially filled orders when cancelled?

The unfilled portion is returned to your vault balance. Any proceeds from the filled portion remain available in your vault.

API

Do I need an API key?

  • Public endpoints (health, tokens, swap quotes) — No API key needed
  • Trading endpoints (place order, swap) — No API key needed, but requires EIP-712 signatures
  • Read endpoints (balances, order history) — API key required

See Authentication for how to create API keys.

What are the rate limits?

Application throttling groups requests by operation. Anonymous traffic uses the trusted peer IP; authenticated traffic can use the resolved owner. API-key wallet limits additionally apply by group: read 10/s, trade 5/s, cancel 2/s, transfer 2/s, quote 50/s. Batch quotes count per item, not only per HTTP request. Edge limits and deployment configuration may add constraints. See Authentication and honor Retry-After when present.

Is there a WebSocket API?

Not currently for public users. Use polling with the REST API for order status updates.

Security

How are funds secured?

Vault custody, user signing checks and role-based contract permissions work together. Emergency withdrawal reduces reliance on API availability but still requires its delay, balance and token-transfer conditions. See Non-Custodial Design.

What if the API goes down?

Call emergencyWithdraw(token, amount) on Sera, wait at least 7,200 blocks, then execute within 14,400 blocks of the request. A smaller positive amount is allowed and consumes the request; calling after expiry starts a new request. See Emergency Withdrawal.

Can my account be frozen?

Compliance screening can block protected API actions, including an API withdrawal request. It does not itself transfer your assets. You can use the on-chain emergency withdrawal flow under its balance, request, delay and execution-window rules. Account reads and signed cancellations have separate access checks; see compliance.

Support

How do I get help?