Detection works differently depending on whether you use Gmail or Outlook. This page covers both, what happens once a subscription is found, how a billing email is actually read, and the things BillSensor will not do.
Gmail and Outlook are not the same feature with a different logo on it. They use different mechanisms, need different things from you, and have different limits. Pick yours.
A content script reads the email already rendered in your own browser tab, the same content your eyes are looking at. There is no Google sign-in, no permission screen and no Gmail API request, so there is nothing to grant and nothing to revoke later.
That you open the billing email. Detection runs at the moment you click into a message, so a receipt that arrives and sits unread is not seen. Anything BillSensor misses can be added from the popup by hand.
Mail you archived or deleted before installing is out of reach, and a Gmail tab that was already open at install time needs one reload before it works. A bulk inbox scan for Gmail is planned but not shipped.
A Chrome notification 7 days before a charge, on every plan. Your free account also covers renewal emails on your 5 lowest-cost subscriptions. Pro and Business add a second warning at 3 days, by Chrome notification and by email. For free trials of seven days or less, the warnings move closer to the first charge so they still arrive in time.
Mail.Read
You connect once through Microsoft's own consent screen. BillSensor then reads your mailbox through the Graph API and scans the last 12 months of billing history in a single pass, rather than waiting for you to open anything.
One approval of a read-only scope. On a work or school account your IT admin may have to approve it first, which is a Microsoft policy setting rather than something BillSensor controls.
There is no passive browser trigger for Outlook the way there is for Gmail, so no Chrome notifications. Alerts arrive by email only. The first scan takes a minute or two.
On Free you re-scan when you want to, using Scan now in the popup. Pro and Business re-scan automatically once a day in the background, so new billing mail is picked up without you asking.
A list of subscriptions is the easy part. These are the things that act on it.
A warning 7 days before a charge lands, so there is still time to decide. Pro and Business get a second one at 3 days, by Chrome notification and by email, which is the last useful moment to act.
Mark a subscription cancelled and BillSensor keeps checking it. If a billing email arrives from that tool dated after your cancellation, you hear about it straight away rather than on a statement weeks later.
You also get a reminder 7 days before the original renewal date, so you can confirm the cancellation actually went through.
Each detected bill is compared against the previous one for that tool. A rise is flagged as a price increase, and anything 20% or more above the last amount is flagged separately as a spike worth looking at.
BillSensor only sees a charge when you open the receipt, so it cannot tell on its own whether a free trial became a paid plan. When a trial ends, it emails you and asks. Answer in one click and it tracks the subscription properly from then on, with trials left out of your spend total.
68 of the 90 tracked tools carry a rating from 1 to 10 for how much effort cancelling takes, drawn from published policies and documented complaints, and the rest are still being researched. Adobe scores 9, largely for its early termination fee on annual plans.
Free covers your 3 lowest-cost subscriptions. Paid plans show the full detail on every tool.
A timestamped record of when you cancelled, saved as a page you can keep or print. If a charge turns up afterwards, that record is what you attach to a dispute.
Monthly and yearly totals across everything detected, in the currency you were actually billed in. Amounts in other currencies are never converted at an invented rate, they are counted separately and labelled.
Most trackers will not tell you this part. It is the difference between a subscription list you can trust and one full of things you never bought.
First the sender domain, matched as an exact domain or a subdomain, never as a loose substring. Then billing processors like Stripe, Paddle or Chargebee, which only count when the subject names the tool and a real billing phrase and a labelled amount are all present. After that, the subject line. Last, the body.
Domain matching is strict on purpose. A looser check once matched a Dropbox receipt against a tool whose domain ended in the same letters, and saved the wrong subscription with the wrong amount.
A tool name appearing somewhere in an email is a mention, not evidence you pay for it. What happens next depends on how the match was made.
BillSensor looks for labels like grand total, total charged or amount paid and reads the figure that follows. If no label is found, the subscription is saved with no amount rather than a guess.
That rule exists because taking the first currency figure in an email picks up discount lines, tax lines and order references. A pre-tax line sitting above the real total is skipped too, so an 18% tax is not quietly dropped from what you are shown. Eight currencies are recognised: USD, EUR, GBP, INR, AUD, CAD, SGD and JPY.
Phrases like next billing, renews on and billed on are searched for a real date. When one is found it is used, and it replaces any earlier estimate. When none is found, the date is worked out from the billing cycle and marked as calculated rather than presented as fact.
Bank and card notifications, bounce messages, support auto-replies, security and verification codes, BillSensor's own mail, and marketing. After all of that an email must still contain a genuine billing phrase, an invoice, a receipt, a payment or a charge, or it is not a detection.
These lists come from real false positives found in production, which is why they are specific rather than tidy.
Worth knowing before you install rather than after.
Across design, marketing, developer, hosting, finance and AI software, with a cancellation difficulty score on 68 of them.
USD, EUR, GBP, INR, AUD, CAD, SGD and JPY, read from the email and never converted.
Chrome, Edge, Brave, Opera and others built on Chromium.
Works across several signed-in accounts at once, without extra setup.
A false positive can be deleted on any plan, and it will not affect the rest of your list.
No card needed. A free account is all it takes.
Free covers detection and 7-day alerts. Pro and Business add the monitoring, records and history. The full breakdown sits on one page, tier by tier.
Install it, open your next billing email, and watch what it pulls out. Free, and nothing to connect on Gmail.