The best Zillow Chrome extensions for real estate investors (2026)

If you screen rentals on Zillow, you've probably searched the Chrome Web Store for something that does the math for you. There are a lot of options, and they fall into three groups that solve genuinely different problems. Here's how to tell them apart so you pick for how you actually work — not for whichever listing ranks first.

1. In-context overlays (analyze on the listing)

These are browser extensions that put investment metrics — cap rate, cash flow, cash-on-cash — right on the Zillow listing you're viewing, usually in a popup or side panel. Their advantage is speed: you never leave the page, so you can screen dozens of listings in the time a web platform takes to load one. The catch with many of them is shallow assumptions and, in some cases, AI-generated numbers that look authoritative but aren't reproducible.

• What to look for: transparent, deterministic math you can check; the ability to edit rent and financing; and real local tax and insurance rather than a flat national average.
• What to avoid: tools that won't show you the formula, or that quietly use one tax assumption for every state — that's where the verdict goes wrong in high-tax markets.

2. Full web platforms (analyze in their app)

Tools like DealCheck and Mashvisor are full underwriting platforms with comps, projections, and reporting. They're powerful and the right choice when you're underwriting a deal you're serious about. The trade-off is context-switching: you leave the listing and re-enter the address into a separate app, which is heavier than you want for fast first-pass screening across many listings.

3. Sourcing tools (find deals, not analyze them)

DealMachine, PropStream and similar are built for finding off-market opportunities — driving for dollars, owner data, skip tracing. They're excellent at their job, but that job isn't on-listing analysis; they answer "where are the deals?", not "is this listing a good deal?"

How to choose

• Screening a lot of listings fast? Use an in-context overlay extension — the speed of staying on the page compounds.
• Underwriting a specific deal in depth? A full web platform earns its weight.
• Trying to find deals in the first place? That's a sourcing tool, a different category entirely.

Where Mortar fits

Mortar is an in-context overlay built around two opinions: the math should be deterministic (no AI guessing your cap rate), and the inputs should be local (real per-state property tax and insurance, not a national average). It analyzes any Zillow listing in about ten seconds, lets you edit rent and financing, and scores the deal against your own buy box. It's free to start. We think it's the most honest option in category one — but the right answer is whichever tool matches how you work.