Global Accounts

Give your customers a branded, self-custodial multi-currency account powered by Grid.

A Global Account is what we consider a programmable, self-custodial account for holding and moving money. Under the hood, it is an embedded Spark wallet that Lightspark provisions for your customer. It can hold different stablecoins, including those denominated in local currencies, as well as other digital assets such as Bitcoin.

In the API, a Global Account is an internal account with type: "EMBEDDED_WALLET". It uses the same customer, quote, transaction, and webhook primitives as other accounts. Receiving funds works the same way, too. To move money out, the customer must authorize the transfer on their device, which signs the payment with a session signing key.

Why a Global Account?

• Self-custodial. Neither Lightspark nor your platform can move funds unilaterally. Outbound transfers require authorization from the customer’s device.
• Stablecoin-denominated. Balances can be held in stablecoins like Brale-issued USDB. You can also issue your own stablecoin and request enablement in Grid. Use the /quotes API to convert from fiat or withdraw through supported payment rails.
• Native. Reuse the customer, internal-account, quote, transaction, and webhook primitives you already use for payouts or P2P. Global Accounts add authentication and signing at the account level.

Payment flow

Global Accounts use the same /quotes and /quotes/{id}/execute pattern as other payments. Outbound transfers also require a client signature.

• Incoming funds. Funding an account works like any other internal account. Create a quote with the Global Account as the destination, execute it, and Grid converts the source currency into USDB and credits the account. Incoming funds do not require customer approval.
• Outgoing funds. Withdrawals and transfers out require the customer to authorize them on their device. Grid returns a payloadToSign in the quote’s paymentInstructions; the client signs those bytes with its session signing key and passes the base64 signature as the Grid-Wallet-Signature header on /quotes/{id}/execute. Only then does Grid release the funds.

Sessions are short-lived (15 minutes by default) and bound to a specific device via the client key pair, so a stolen signature can’t be replayed from a different device or after the session expires. Standard transaction webhooks fire throughout the lifecycle. See Transaction lifecycle.

Architecture

Three parties participate in every signed action:

Party	Role
Client	The customer’s device (browser, iOS app, or Android app). Generates the client key pair, runs WebAuthn, decrypts the session signing key, and signs outbound requests.
Integrator backend	Your server. Holds your Grid API credentials, brokers every call to Grid on behalf of the client, and issues WebAuthn challenges for initial passkey registration.
Grid	Verifies auth credentials, issues session signing keys (encrypted to the client’s public key), and enforces that every account action is authorized.

The client never talks to Grid directly. Every request flows client → integrator backend → Grid.

Auth credentials, client keys, and session signing keys

Three distinct pieces of crypto collaborate to authorize actions on the Global Account (withdrawals, credential changes, session revocations, wallet exports, and wallet privacy updates):

Piece	Where it lives	How long it lives	What it proves
Auth credential: passkey, OIDC token, or email OTP	Registered on the account; the passkey itself lives on the authenticator, OIDC on your IdP, OTP in the user’s inbox	Until the customer revokes it	”I am the human who owns this account.” Used to authenticate the user at the start of each session.
Client key pair (P-256)	Generated on the client device for each session-issuing or export request; private key stays in device-local secure storage	One authentication, session refresh, or wallet export	Binds a given session signing key or wallet export delivery to the exact device that asked for it. Grid encrypts the response to this public key, so only this device can decrypt.
Session signing key (P-256)	Issued by Grid, sealed to the client public key, decrypted and held on the device for the session’s lifetime	15 minutes (default)	“This specific account action was approved on an authenticated device.” Builds Grid wallet signatures over the payloadToSign Grid returns on quotes, credential changes, session refresh/revocation, wallet exports, customer email updates, and wallet privacy updates.

The flow is always the same: verify an auth credential → receive a short-lived session signing key → build a Grid wallet signature over the payloadToSign bytes on the client → pass that signature as the Grid-Wallet-Signature header on the request that actually moves funds or changes account state. This applies to withdrawals, adding or removing credentials, refreshing or revoking sessions, exporting the wallet seed, updating customer email for tied email OTP credentials, and updating wallet privacy.

Core capabilities

Additional capabilities

Some Global Accounts capabilities require platform enablement before you can build with them. Book a demo to see how they fit your platform.

Where to next

Implementation overview

End-to-end walkthrough: create a customer, register a passkey, fund the account, and execute a signed withdrawal.

Agents (experimental)

Native Grid support for connected AI agents, managed permissions, and partner approval surfaces.

Authentication

Passkey, OAuth (OIDC), and email OTP registration and reauthentication flows.

Client keys & signing

Generate the P-256 key pair, decrypt the session signing key, and sign payloads on Web, iOS, and Android.

Sandbox testing

Magic values for OTP and signatures, plus sandbox OIDC token rules that exercise the full request shape without standing up real auth providers.