Fintech and payments Case study
Rainbow: options trading and risk platform
A .NET trading engine, API and Next.js control console for Rainbow Capital that runs configurable US equity options strategies under per-underlyer risk limits, with daily profit and loss reports to Slack.
- Next.js
- React
- TypeScript
- ASP.NET Core
- .NET
- Client
- Rainbow Capital
- Service
- Web apps, Integrations
- Years
- 2023–2024
- Stack
- Next.js, React, TypeScript, ASP.NET Core and 8 more
- Platforms
- Web
Overview
Rainbow runs automated options strategies on US equities. A .NET 8 engine finds option spreads, generates target positions and works out risk scenarios, and an API and a Next.js console let operators sign in, see their strategies and change their parameters. A separate tracker posts the daily profit and loss report to Slack.
The challenge
Several strategies run against live market data, each with strict risk limits per underlying. Operators need to start, stop and tune them safely from a browser, and the team needs the day's results without checking by hand.
What we built
- A strategy engine with lifecycle states and a market open and close monitor
- Spread finding for call, put and complex option spreads
- A target position generator with a work queue
- A position risk manager and risk scenario calculator
- An integration layer with the market data and order vendor
- A REST API with JWT sign-in for starting, stopping and configuring strategies
- A PostgreSQL schema with versioned migrations
- A Next.js console: sign-in, environment, strategy list and a strategy detail editor
- A profit and loss tracker with a daily job, file reports and Slack posting
- Handling of NYSE market holidays
- A deployment pipeline with GitHub Actions, Docker Compose and nginx with TLS, and automated tests
How a system like this fits together
Reference architecture: options trading and risk platform
Simplified reference architecture, not a client schematic.
- An operator signs in to the Next.js console, and the console calls the ASP.NET Core strategy API over REST with a JWT.
- The operator starts, stops or tunes a strategy; the API passes the command to the strategy engine.
- The engine finds option spreads in live market data from the market data and order vendor and sends orders back through it.
- It works out target positions and risk, keeps each underlying within its risk limits, and reads and writes configuration and results in PostgreSQL.
- A separate profit and loss tracker runs a daily job, writes a file report and posts the day's profit and loss to Slack.
Technology used
| Layer | Choice | Purpose |
|---|---|---|
| Front end | Next.js, React, Tailwind CSS | operator console |
| API | ASP.NET Core, JWT | strategy control and sign-in |
| Engine | .NET libraries | spreads, positions and risk |
| Data | PostgreSQL, Entity Framework Core | configuration, results and users |
| Operations | Docker Compose, nginx, GitHub Actions, Slack | deploy and alert |
What happened next
- Delivered
The work described above was delivered to the client.
- Operational facts
- Our work on this project spanned 2023–2024.
Could this be your project?
- You need a web application with user accounts, admin tools and reporting. Website and web app development
- Your product has to connect to payment, accounting, messaging or other third-party systems.
- You work in fintech and payments and want a team that has built for it before. Fintech and payments work
Questions about this project
How long did this project take?
Our work on it ran from 2023 to 2024.
What technology was used?
Next.js, React, TypeScript, ASP.NET Core, .NET, C#, PostgreSQL, Docker, Entity Framework Core, Tailwind CSS, nginx, GitHub Actions.
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