TheoryCraft vs QuantConnect (2026)
QuantConnect is built for programmers writing LEAN code. TheoryCraft is AI-assisted research you can also code by hand.
QuantConnect is the closest open-source quant rival to TheoryCraft, and the two share a lot. Both run an AI assistant, expose an MCP server, and ship an open-source engine.
The difference is who they are built for. QuantConnect is built for programmers writing against the LEAN API: you bring the code, Mia helps. TheoryCraft is AI-assisted research you can also code by hand: you describe an idea, the assistant drafts the Python, and you can read and edit every line.
TheoryCraft adds two things QuantConnect leaves to you. Scientific validation is built in: walk-forward, Monte Carlo, and overfitting checks come standard, instead of code you wire up yourself.
And the data covers ground QuantConnect does not. TheoryCraft includes market data for forex, EU and US equities, metals, commodities, and indices, 1,600+ instruments via Dukascopy Bank, where QuantConnect's data is US-focused with no EU exchanges.
TheoryCraft vs QuantConnect: feature comparison
| Feature | TheoryCraft | QuantConnect |
|---|---|---|
| AI drafts your strategy from a plain-language brief |
Describe the idea; the assistant writes and runs it, and you keep full control of the code
|
Mia writes LEAN code from a brief
|
| Standard, portable Python (runs anywhere) |
Readable code you can export and run anywhere, with no lock-in
|
Readable Python and C#
|
| Connect your own AI agent (Claude, Cursor, Codex) via MCP |
Native MCP server
|
First-party MCP server
|
| Open-source engine (Apache-2.0) |
Free to inspect, fork and run
|
LEAN engine, Apache-2.0
|
| Self-host the open-source engine |
Run the Apache-2.0 core on your own machine
|
Run LEAN locally via the CLI
|
| Historical strategy backtesting |
Across years of market data
|
Cloud backtesting on bundled data
|
| Multi-asset markets |
Forex, equities, metals, commodities, indices
|
US equities, options, futures, crypto
|
| Parameter optimization |
Matrix and genetic search
|
Parameter optimization
|
| Flexible LLM access (included, or your own key) |
Model included on the Managed plan, or your own key across 26 providers
|
Mia runs on metered credits, with a narrower set of providers
|
| Scientific validation (walk-forward, Monte Carlo, overfit checks) |
Layered Edge, Filters and Risk, each tested independently
|
Backtesting and research, but you build walk-forward and overfitting checks yourself
|
| Market data included (1,600+ instruments) |
Forex, EU and US equities, metals, commodities, indices via Dukascopy Bank
|
Huge US data, but no EU exchanges
|
AI on TheoryCraft vs QuantConnect
Both platforms run an agentic AI. QuantConnect's Mia writes LEAN code, launches backtests, and debugs, aimed at programmers who already know the LEAN API. TheoryCraft's assistant works from the other direction.
- AI-assisted research, not LEAN programming. Describe an idea and the assistant drafts the Python, runs the backtest, and reads back the results. You can read and edit every line, and you can write the code yourself.
- Flexible LLM access. Use the model included on the Managed plan, or bring your own key across 26 providers (Anthropic, OpenAI, Gemini, Mistral, Groq, and more). Mia runs on metered credits with a narrower set of providers.
- Bring your own agent. Connect Claude, Codex, Cursor, Windsurf, VS Code, or Gemini CLI to your research workspace over MCP, the same way QuantConnect exposes its first-party MCP server.
Same core idea, an AI that turns words into a tested strategy. TheoryCraft tilts it toward research you can read and validate, on the model you choose.
Why traders move from QuantConnect to TheoryCraft
AI-assisted research, not code-first LEAN
QuantConnect is built for programmers writing against the LEAN API, which carries a real learning curve. TheoryCraft lets you describe a strategy in plain language and drafts the Python for you. It stays real, readable Python you can edit, so you are never locked out of the details.
Scientific validation built in
On QuantConnect you get backtesting and research, then build walk-forward, Monte Carlo, and overfitting checks yourself. TheoryCraft ships that validation by default, with the Edge, its Filters, and its Risk rules each tested on their own.
LLM access on your terms
TheoryCraft gives you the choice: the model included on the Managed plan, or your own key across 26 providers, your billing, your model. QuantConnect's Mia runs on metered credits with a narrower set of providers.
Data that covers Europe and forex
TheoryCraft includes market data for forex, EU and US equities, metals, commodities, and indices, 1,600+ instruments via Dukascopy Bank. QuantConnect's data is US-focused with no EU exchanges, so European markets are a gap on its side.
Stop guessing. Start proving.
Turn an idea into evidence. Build it, backtest it, and see whether the edge is real before you risk capital.
Frequently asked questions
Is TheoryCraft a good QuantConnect alternative?
Yes, if you want AI-assisted research rather than code-first LEAN programming. Both run an AI assistant and an open-source engine. TheoryCraft adds built-in scientific validation, flexible LLM access, and European market data that QuantConnect lacks, while still handing you real, readable Python.
Do I need to code against the LEAN API like on QuantConnect?
No. QuantConnect is built for programmers writing against the LEAN API. On TheoryCraft you describe a strategy and the assistant drafts the Python for you. You can read and edit the code, and you can write it by hand, but you never have to learn a proprietary API to get started.
Does TheoryCraft validate strategies more than QuantConnect?
On QuantConnect you get backtesting and research, then build walk-forward and overfitting checks yourself. TheoryCraft ships that scientific validation by default, with walk-forward, Monte Carlo, and overfitting checks, and each layer of a strategy tested independently.
Can I use my own LLM key instead of metered AI credits?
Yes. You can bring your own key across 26 providers, or use the model included on the Managed plan. QuantConnect's Mia runs on metered credits with a narrower set of providers.
Does TheoryCraft cover European markets and forex?
Yes. TheoryCraft includes market data for forex, EU and US equities, metals, commodities, and indices, 1,600+ instruments via Dukascopy Bank. QuantConnect's data is US-focused with no EU exchanges, so European coverage is a real difference.