OTL: the Open Transaction Layer for compliant onchain transactions

A Solana transaction settles in well under a second and tells you exactly what moved between which accounts. What it doesn't tell you: who controls the receiving wallet, whether they're a sanctioned entity, what off-chain invoice this payment corresponds to, or whether the counterparty's institution will accept the funds under Travel Rule. Every institution has built that coordination layer alone, in private.

OTL — the Open Transaction Layer — is an open protocol stack to standardize that layer once. Founded by Fireblocks, it's explicitly chain-agnostic and applies to Solana the same way it applies to any other settlement layer.

The gap it fills

OTL's framing: "Blockchain infrastructure is built. The coordination layer for secure, compliant transactions isn't." The chain is the settlement layer. OTL is everything that has to happen around settlement so two regulated counterparties can transact safely — discovery, identity, compliance, payment coordination, reconciliation.

The 5-layer stack

OTL borrows the OSI mental model: four foundational layers, plus an application layer where business logic lives. Lower layers answer who you are, how you connect, how data moves; the top layer is where you actually do something.

┌─────────────────────────────────────────────┐
│ 5. Application   end-to-end flows             │  Universal Deposit,
│                  (identify → coordinate →      │  Wallet Attribution
│                   pay → comply → settle)       │
├─────────────────────────────────────────────┤
│ 4. Messaging     structured payloads          │  ISO 20022, IVMS101
├─────────────────────────────────────────────┤
│ 3. Transport     how data moves               │  WalletConnect-style
├─────────────────────────────────────────────┤
│ 2. Session       authenticated channels       │
├─────────────────────────────────────────────┤
│ 1. Identity      who is the counterparty?     │  W3C DID
└─────────────────────────────────────────────┘

• Identity — the base everything depends on: identifying a counterparty and authenticating their messages, built on W3C DID (decentralized identifiers).
• Session / Transport — establishing authenticated channels and moving data between parties (drawing on standards like WalletConnect).
• Messaging — structured payloads regulated institutions already understand: ISO 20022 for payment messaging, IVMS101 for Travel Rule data.
• Application — composes the lower layers into a complete flow where counterparty identification, payment coordination, and Travel Rule compliance are built into every interaction rather than bolted on.

Importantly, OTL doesn't invent new identity or messaging primitives — it composes existing, adopted standards (DID, IVMS101, ISO 20022, WalletConnect) into a transaction lifecycle.

The first two applications

The stack ships with two concrete open applications first:

• Universal Deposit — a standard way to initiate and coordinate a secure payment from any wallet (custodial or non-custodial) with compliance rails included. Instead of every exchange and fintech reinventing deposit flows, you get one protocol for "pay this address, here's the compliance context, here's how to confirm receipt."
• Wallet Attribution — a decentralized way to identify the entity controlling a blockchain address before transacting, replacing the proprietary "attribution waterfall" each institution maintains today. For a Solana address, this answers "is this a Coinbase wallet, a self-custody wallet, or a sanctioned entity?" before you send.

Where Solana fits

OTL is chain-agnostic by design, but its lineage runs straight through Solana. It grew out of the Blockchain Payments Consortium (BPC) that Fireblocks initiated in December 2025 — whose members include the foundations behind Solana, Monad, Polygon, Stellar, Sui, and TON. The founding institutional roster reads like the settlement side of crypto: Robinhood, MetaMask, SoFi, Checkout.com, Stripe-owned Privy + Bridge, Cross River Bank, FalconX, Wintermute, B2C2, eToro, Securitize, WalletConnect, zerohash, and more.

For a Solana developer, the practical read is: if you're building institutional payments, deposits, or compliance flows on Solana, OTL is the emerging standard for the coordination around your on-chain settlement — and the Solana Foundation is at the table defining it. Wallet Attribution in particular is something every serious Solana payments product currently hacks together from labeling datasets.

The honest read

OTL is a specification and consortium, not a deployed protocol you can npm install today. The working specs are public and open source at otl.network, but it's early — the value depends entirely on adoption, and standards backed by big-name founders have a mixed track record of shipping. It's also unapologetically aimed at regulated institutions: if you're building a permissionless DeFi protocol, the Travel-Rule and attribution machinery is overhead you don't want.

But the gap is real. Every fintech touching crypto has rebuilt identity, compliance, and deposit coordination privately. Standardizing that — on top of standards institutions already trust — is a credible bet, and having the Solana Foundation among the backers means Solana won't be a second-class citizen in it.

References

• otl.network — specs and Flow Explorer
• Fireblocks — "The Missing Onchain Standard"
• x402 — permissionless API payments (the opposite design point)
• Stablecoins on Solana — what settles under all of this

x402 makes payments permissionless; OTL makes them compliant and coordinated. They're aimed at opposite ends of the same problem — and both treat Solana as a first-class settlement layer.