Portfolio backtesting you can trust.
Rearview is a Mac app that tests your trading rules on past prices, across a whole portfolio: stocks and ETFs, coins, futures and forex, on daily bars or down to the minute. It can’t see future prices, it gives the same answer every run, and it tells you when a result is probably luck.
30 days free, no card · Buy once, no subscription · Apple silicon, macOS 26 or later
Every screenshot shows the synthetic sample data that comes with the app.
Results you can trust
It can’t see tomorrow.
On each day a strategy sees only what was known at that day’s close. Before every release the whole pipeline is replayed on data cut off at thousands of dates, and every decision has to come out the same.
The same answer every run.
Cash and shares are counted exactly, and parallel work adds up in a fixed order, so a result is identical on one core or eighteen. Every saved run reruns from its own folder.
Checked against a second engine.
A separate engine, written from the engine’s rules and hand-worked cases without seeing its code, has to match every trade and every cent. Three open-source backtesters, vectorbt, bt and QuantConnect’s LEAN, agree on the cases they can model.
Inside Rearview.
One window for the script, its results, every trade, your scans, your live account and every run you’ve kept.
Each line shows what it did.
A strategy is one short plain-text file, so your scripts live in a folder and work with git, and every line shows its figures from the last run. The editor completes what you type, and the language reference is one page an AI coding agent can read; rvw check --json lets it check its own scripts. The language › 42 examples ›
Real portfolio testing.
Rank and trade across hundreds of stocks a day, with position limits, rebalancing and a buffer that keeps holdings while they still rank. Run two to eight strategies in sleeves or one pool of cash. Long and short, with borrow fees and margin. The Timeline puts equity, drawdown, exposure, the benchmark’s trend and every trade on one clock. Results ›
Every trade, up close.
Step through a run’s trades with the arrow keys, each on its own chart with the entry and exit marked. See them by exit reason, as a distribution, or by how far each went against you first, and where the money came from by security and sector. Export a run as a self-contained HTML report.
Scan the market every evening.
A short script lists the securities that meet your conditions on a day, with every value it worked out, best ranked first. Step a day back, scan a range of days, and export the rows as CSV. How scans work ›
Your own trading, beside the backtest.
Import an Interactive Brokers Flex file, or any broker’s fills as a simple CSV. Rearview replays them beside the backtest of the same days, then writes the next session’s orders sized from your real account, as a list or an Interactive Brokers basket. It never places an order. The account pictured comes from a broker file made up for it. Live accounts ›
Every run kept. Every run reproduces.
Each run is saved with its script, settings, engine version and a fingerprint of its data. The Runs library sorts, flags, tags and searches them, and compares any two side by side, with a warning when they aren’t like for like.
Your data, done right.
Bring the data you already pay for, or start with free exports. Rearview converts per-symbol files, futures contracts and Sharadar’s tables, and an export script brings in Norgate Data. It works out adjusted prices itself, finds gaps, price jumps and missing splits, and keeps earlier runs reproducing when the data updates. Importing ›
Is this result luck?
Search a strategy’s settings and Rearview counts every variation you tried, earlier runs and previews included. It reports the Deflated Sharpe Ratio and the Probability of Backtest Overfitting with every input shown, then says it plainly: probably not luck, can’t tell, or probably luck.
Deflated Sharpe, 97%. The rule family seems to earn something, even after counting all 50 settings tried.
PBO, 82%. The setting that looked best in one half of the history ranked below the median in the other half 82% of the time.
Probably luck. Which setting is best is noise, and that is the part you would pick. The verdict lists every input.
Set any run against 500 runs that enter at random at its own rate. Stress-test it with costs doubled and signals a day late. Hold the latest years back in a lockbox, and walk it forward: pick settings on the past and trade them on what came next. Research ›
Stocks, coins, futures and forex.
Each market trades on its own days under the engine’s written rules, and the second engine checks them all.
Exchanges around the world
Hold US stocks beside London’s or Sydney’s, each on its own exchange’s days. Exchanges ›
Your account’s currency
Dollars, pounds, euros or any currency your data has a forex pair for, at the day’s rate. Currencies ›
Coins
Every day of the week, in fractions down to a hundred-millionth, long only. Coins ›
Futures
Chains that roll from one contract to the next and settle at every close. Futures ›
Forex
Pairs that settle daily and earn or pay carry from both currencies’ rates. Forex ›
Bars down to a minute
Intraday stocks and ETFs, the time of day, and flat at the close, half days included. Intraday ›
Buy it once. Keep it.
No subscription and no data markup. Your licence is checked on your Mac, the version you buy keeps working, and if Rearview is ever discontinued, a final version ships with the licence check removed.
Trial
Free
30 days from your first backtest, scan or check. No card.
Licence
$349
Once, with every update released in the next 12 months.
Founder price
$249
For the first 50 buyers, to the end of 12 January 2027 at the latest.
Update renewal
$149
A year, if you want it. The app keeps working without it.
Prices in US dollars; tax is added where the law requires it. Correctness fixes are free to every licence holder. Pricing ›
Try it free for 30 days.
The trial starts at your first backtest, scan or check, and no card is needed. It comes with ten years of synthetic sample data to try everything on.
A native Mac app for Apple silicon, macOS 26 or later. No account, no telemetry: your strategies and data stay on your Mac.