InterposeInvest

Platform & Architecture

Engineered to sit on top of what you have.

Interpose takes no custody. Both experiences — wealth management and self-directed — run over the custody you already hold, through one gateway, event-sourced, API-first and auditable end to end. Whether you're an advisory firm unifying three custodians or a brokerage platform adding an advisory layer, this is the same architecture.

API-FirstEvent-SourcedBaaS-Gateway ModelBring-Your-Own CustodyCloudEvents 1.0

Design Principles

Engineered like infrastructure, not an app.

API-first

Every capability is a REST endpoint before any UI exists, with event streams alongside it. OpenAPI 3.1 is the source of truth — generate a client in any language.

Event-sourced

Positions are always derived from an immutable transaction ledger — never overwritten. Every state change emits a CloudEvent, giving you a complete, replayable audit trail.

BaaS-gateway model

The PM layer never connects to a custodian directly. All custody protocols — FIX, REST, SFTP, CSV — terminate at the BaaS gateway, so there is one integration surface, not N.

Cloud-native & modular

Stateless, horizontally-scalable services with clean interface contracts. Take the PM layer, the investing app, or both — no hidden coupling forces an all-or-nothing adoption.

The Gateway Model

One integration surface. Every custodian behind it.

Both front ends talk to a single gateway. The gateway owns every custody protocol — so adding a custodian never changes the PM layer, the portals, or the app.

Interpose Invest · white-labeled as your product

Wealth ManagementSelf-Directed AppRebalancingGIPS PerformanceDirect IndexingWhite-Label Portals

BaaS Gateway · single integration surface

Normalizes positions, transactions, and orders · owns FIX / REST / SFTP / CSV · routes rebalance orders to execution · enforces compliance checks

Your Native BaaS

you keep custody

Correspondent Custody

you keep custody

RIA Custodians

you keep custody

Crypto Custody

you keep custody

Interpose holds no assets. The broker-dealer or custodian of record is you or your custodian.

One Book Of Record

Every custodian, in one table, with the same columns.

Cash, positions, total value, cash weight, assigned portfolio and drift — computed the same way whoever holds the assets. The custodian is a column, not a separate system with its own reconciliation.

Latency is stated per connection rather than averaged away: an API custodian refreshes on demand, a file-delivered one is as fresh as its last drop.

Account table listing each account with its custodian, cash balance, position balance, total value, cash weight, assigned portfolio and drift
One account table across custodians — same columns, same arithmeticSandbox tenant · seeded book

Multi-Custodian Connectivity

Aggregate every custodian into one data model.

Register a connection per account and the gateway pulls positions and transactions into a single normalized view — no matter where the assets actually sit.

Ingestion modes

APIFeed-bound

On-demand REST/FIX pull where the custodian exposes it — the preferred path. A sync is triggered, not streamed.

FILE_IMPORTT+1 (feed-bound)

Scheduled CSV / SFTP ingestion for custodians without a live API.

Order routing for every custodian flows back through the gateway's execution path — the PM layer emits proposed orders; the gateway handles the per-custodian protocol.

Canonical normalization

  • Typed security identifiers — CUSIP, ISIN, ticker, or contract address — never a bare string
  • Monetary amounts as 4-decimal strings; share quantities as 8-decimal strings — never floats
  • Corporate-action timing quirks handled per custodian before data reaches your API
  • Equities, funds, and alternatives resolved to one canonical position model
{
  "security":  { "type": "cusip", "value": "037833100" },
  "quantity":  "125.00000000",
  "market_value": "23145.7500",
  "currency":  "USD"
}

Custodian-agnostic by design: bring your own brokerage rails, correspondent custody, or the outside custodians your advisors already use. Crypto assets flow through qualified third-party custody only — Interpose never self-custodies.

Two Operating Modes

Identical capabilities. Honest latency.

Every capability is the same in both modes. We're explicit that overlay mode is bound by the custodian's feed cadence — no real-time claims we can't keep.

DimensionReal-timeIntegrated ModeFeed-boundOverlay Mode
Position sourceShared event bus (CloudEvents)Gateway pull from custodian
Update latencyReal-timeFeed-bound — typically T+1
AUM & driftLive on every fillRefreshed on each sync
RebalancingFull engineFull engine
Performance & billingFull engineFull engine
Order routingThrough gatewayThrough gateway

Real-Time Event Streams

Every state change is an event your systems can subscribe to.

In integrated mode, rebalances, fills and position changes are published as CloudEvents 1.0. The transport reachable from your own infrastructure today is Server-Sent Events over ordinary HTTP — no upgrade, no special client, and it survives the corporate proxies that block WebSockets.

Because positions are event-sourced, you can replay the full history of any account to reconstruct state at any point in time — the foundation for a clean audit and for reconciliation that catches breaks the moment they appear.

com.interpose.baas.order.filledcom.interpose.baas.position.updatedcom.interpose.pm.rebalancing.orders.created
POST/api/v1/pm/custodians/connections
POST/api/v1/pm/rebalancing
GET/api/v1/pm/accounts/{id}/performance
POST/api/v1/pm/billing/runs
GET/api/v1/baas/events/trades

Compliance as Code

Regulatory rules that execute, not sit in a PDF.

Wash-sale windows, Reg-T, PDT, Reg SHO, and OFAC screening are versioned, tested policy — checked synchronously, with machine-readable rejection codes your systems can act on.

Wash-Sale (30-day)Reg-T Buying PowerPDTReg SHO LocateOFAC / AMLWrite-once ledger (17a-4 offsite archival on roadmap)GIPS MethodologyPer-Firm Data Isolation

For Brokerage & Custody Platforms

You own the rails. You're missing the front end.

If you run custody, clearing or execution and your customers keep asking for portfolio management or a consumer investing app, this is the same platform approached from the other side.

You keep everything regulated

Custody, clearing, execution, the balance sheet, the customer contract and the broker-dealer licence stay with you. Interpose supplies software and takes no custody, so nothing about your regulatory posture changes.

Two front ends, one integration

An advisory stack for the RIAs and wealth firms on your rails, and a self-directed experience for the consumer channel — both white-labeled, both over a single custodian connection.

No front-end org to build

Portfolio management and a consumer investing app are each a multi-year build with a team attached. This is an integration and a partner engineer instead.

Sandbox first, contract later

The fastest route is a working integration against your sandbox before any commercial conversation. We would rather show you a running system than a deck.

Start a platform conversation

See It For Yourself

Reading about it is the slow way.

Take a sandbox firm and click through the gateway model, the custodian view and the event stream on a seeded book. If you want the architecture walked through, ask — you get the person who designed it.

Start in SandboxTalk to us