An order management system your fund actually owns.
Fillside runs the full trade lifecycle — order staging, pre-trade compliance, FIX routing to brokers, allocations, and real-time positions — on a cluster the fund deploys itself. Orders, positions, and P&L never leave your boundary. AI agents work the desk with full provenance, but no model sits in the order path.
What Fillside is
Institutional OMS workflows, on infrastructure you control.
Fillside targets the workflows buy-side desks actually run — the same ground SS&C Eze, Charles River, and Enfusion cover — and differentiates on three things the incumbents can't offer without cannibalizing their own hosting revenue.
You run the instance.
Deploy Fillside on your own Kubernetes cluster from the same Helm chart we ship. Compliance and IT audit the deployment they run, not a vendor's SOC 2 letter. Nothing about the book sits in a multi-tenant SaaS.
Agents that stage, humans that commit.
A first-class MCP surface lets agents query blotters, run pre-trade what-ifs,
stage baskets, and draft allocations. Every agent mutation carries
decided_by, authority, and
evidence — or it's refused.
No LLM ever sits in the order path.
An open core, not a black box.
The Fillside core is AGPL-3.0. Read the code that routes your orders, fork it, run it forever. Revenue attaches to connectivity, hosting, and the trained execution brain — never to locking you into the software.
Capabilities
The trade lifecycle, end to end.
Feature scope for the first sellable release. US cash equities and ETFs first, with listed options, futures, FX, and digital assets on the expansion path.
Order management
Staging, real-time blotters, baskets and list trading, cancel/replace, care and DMA, block orders, multi-PM and strategy tagging.
Pre-trade compliance
Rule engine, restricted lists, concentration and exposure limits, four-eyes overrides with a full audit trail.
FIX & broker connectivity
A QuickFIX 4.2/4.4 gateway with direct broker sessions, drop-copy ingest, and a hard kill switch below every intelligent layer. Interactive Brokers is the first target counterparty, over API and FIX, with certification on the roadmap.
Allocations & ops
Average-price and pro-rata allocation schemes, commission tracking, confirms and affirms on the roadmap.
Positions & P&L
Real-time positions, intraday P&L, and exposures built from live fills — multi-currency, reconciled against broker and custodian files.
MCP agent surface
Ask "what's our net exposure to semis right now?", stage a basket, or draft allocations — all through a governed, provenance-checked MCP interface.
Audit & records
Append-only, hash-chained audit with retention export and threshold monitors. Books-and-records posture from day one.
Mobile companion
An Expo/React Native app for blotter monitoring, on-the-go order approvals, and push alerts on positions and P&L.
Open source
Free software. Revenue on the layers you can't fork.
The order management core is free and open source. Certified per-broker connectivity, managed hosting, and the per-instance execution brain are the commercial layers — the operations, relationships, and trained models that a license can't hand you. Market data stays bring-your-own at every tier.
Company
Built by Amity Coast.
Fillside is a product of Amity Coast LLC, a software company building sovereign, AI-native infrastructure. Fillside is designed to integrate with executing brokers over FIX and broker APIs as a third-party order management system, with broker certification and authorization in progress; it is not a broker-dealer and does not take custody of assets or funds.
The product is in active development. If you run a desk — hedge fund, RIA, family office, or prop shop — and want sovereignty and AI on your terms, get in touch about early access and design-partner slots.