Ross Taylor Launches BackSearch for Historical Web Searches
Tool provides historical web data via as_of date to avoid future leakage in backtesting.
Entities: BackSearch
Ross Taylor, co-founder and CEO of General Reasoning and former Meta AI lead on Llama models, announced BackSearch. The tool accepts an as_of date to return web information from a chosen past time, preventing future data leakage when backtesting AI agents and reinforcement learning environments that use web search. Developed with lead contributor Ranko and feedback from Shashwat Goel and others, it enables realistic historical simulations for agent training without compromising evaluation integrity.
To predict the future, typically you backtest a strategy on historical data, eg financial time series. This is problematic for agents where ideally you’d like them to get world information from the web - but default web search tools leak future information. BackSearch is the answer for this: it has exactly the same shape as standard web tools, but the user can set an as_of date to simulate web information at a point in time. Note that for LLMs there is a dance to be had as LLMs can get information through pre-training - and are increasingly good at memorising it - so you typically have to configure your BackSearch date to align with the language model cutoff. We’ve been using this internally for RL environments to train our models, but we wanted to test if there is wider interest. For now we release a narrow index focused on news for 2026. Based on interest we can expand it to new domains and longer backdated horizons. Let us know what you think.
🔍 Introducing BackSearch. LLMs are increasingly asked to predict the future, but a good backtest requires a snapshot of the internet at a point in time. BackSearch allows LLMs to search the web as it was on a particular date. It’s great for: 🔮 Forecasting and prediction markets. 📈 Quantitative finance. 🌍 RL environments that simulate the world. 🥶 Freezing websearch for benchmark reproducibility We’re releasing a narrow slice of our index to begin with, focused on the news domain for 2026. Based on feedback we’ll open up more of our index in subsequent releases. 👇 Try BackSearch out with the link below.