Available on Microsoft Edge Add-ons. For Chrome, follow the two-minute source installation guide.
The side panel while reading an email. The people and company are fictional.
Works with
Gmail
Outlook on the web
LinkedIn
Chrome
Microsoft Edge
How it works
One setup, then it reads your inbox
Install the extension, paste one provider key, and every email you open shows who is behind it.
Reads the open email
The sender and everyone in To and Cc. The body is only scanned locally for a linkedin.com/in link.
Cheapest source first
A waterfall from a free signature scan to paid providers, cheapest first. Misses are free and a hit stops the chain.
One key is enough
treg for the cheapest lookups, Monid for the best coverage. Any single key runs the whole flow.
The whole thread
Other senders, To and Cc are listed in the panel, and each person is looked up only when you click them.
Connect on LinkedIn
The panel opens the profile and fills in your note. You click Connect and Send yourself; the extension never does.
Cache and history, locally
Results stay in your browser’s IndexedDB for 90 days, exportable as JSON or CSV and removable in one click.
Privacy
Your inbox stays yours
A lookup goes from your browser straight to the provider you chose. This is exactly what stays here, what leaves, and what the anonymous counts contain.
Your browser
keys · cache · history
the lookup you asked for
No SenderFinder server in the lookup path
The provider you chose
receives the email address, plus the display name and company domain for the Apollo step
Anonymous daily usage counts → SenderFinder statistics service (on by default, can be switched off)
Diagram: your browser holds the keys, the cache and the history. One arrow leaves it: the lookup you asked for, sent to the provider you configured. A crossed-out box marks the SenderFinder server that is not in that path, and a side note explains the anonymous daily usage counts.
Stays on your device
Your provider keys, in the extension’s own storage
Cache and history, in IndexedDB (90 days, 5,000 entries)
Settings, caps and the automatic-lookup limit
Which emails you read: nothing about it leaves the browser
Goes to the provider you chose
The address you look up, with your key
The display name from the mail header
The company domain, for the Apollo step
That provider’s catalog price request
Anonymous usage counts
On by default; one switch in settings turns them off
Daily totals: counts, outcomes, spend, version, language
A random installation ID, deleted when you switch them off
Never an address, name, domain, key or message text
Best for: the default; cheapest step first, Apollo as backstop
BlitzAPI → Hunter → QuickEnrich → Apollo
96% found
Monid only
$0.0220
per found address, paid to the provider
Best for: hit rate
Hunter → Apollo
91% found
Estimated monthly cost
— month
Cost per new address
—
Work addresses found
—
Found per month
—
Found means a profile came back with a matching name. The two keys differ mainly in how often the expensive fallback is needed.
Caps still apply: $2 per day and $0.05 per lookup by default, both adjustable in settings. The estimate assumes 30 days and one lookup per new address.
Example volumes
Shown without JavaScript. Same model, same prices: 20% of the senders are personal or role addresses and are skipped.
Both keys
10 a day
≈ $2.39 / month ≈ 96% found
30 a day
≈ $7.18 / month ≈ 96% found
100 a day
≈ $23.95 / month ≈ 96% found
treg only
10 a day
≈ $0.17 / month ≈ 58% found
30 a day
≈ $0.51 / month ≈ 58% found
100 a day
≈ $1.71 / month ≈ 58% found
Monid only
10 a day
≈ $5.28 / month ≈ 91% found
30 a day
≈ $15.83 / month ≈ 91% found
100 a day
≈ $52.78 / month ≈ 91% found
Turn on JavaScript for your own numbers. Everything above is a plain table, not a promise of spend.
Where the numbers come from
Every new sender address is looked up once and cached. Repeat senders cost $0, so the input is new addresses per day, not emails read.
Per-hit prices are the provider catalog prices on 25 October 2026: BlitzAPI $0.0005, QuickEnrich $0.0048, Hunter $0.0049, Apollo $0.026. Misses are free on these steps.
Per-step hit rates come from the 50-address benchmark of 25 October 2026: 48 % solved by BlitzAPI, then 19 % of what was left by the next step, 19 % of the remainder by the step after that. Apollo answered 17 of the 19 addresses it was called for.
With both keys that gives about 95 % of work addresses found, against 48 of 50 (96 %) measured. With treg alone only the two cheap steps run, with Monid alone Hunter and Apollo run.
Monthly cost = new addresses per day × (1 − skipped share) × 30 × cost per address. The free email-signature scan, the optional Village and ContactOut steps and Firecrawl are not included.
These are estimates from one benchmark of English-speaking sales and growth contacts. Your own inbox may behave differently.
Prices and hit rates: 25 October 2026. The extension re-reads the catalog price before every call, so a provider price change shows up immediately.
Estimates from the 50-address benchmark of 25 October 2026. Defaults: $2 per day and $0.05 per lookup, both adjustable in settings.
Longer ones live in the install guide and the privacy statement.
Is it free?
Yes. The extension is free and open source under the AGPL-3.0 license, with no account and no subscription. Paid lookups are optional: the data provider you choose bills them to your own key, per hit, within the caps you set. The signature scan and the cache cost nothing.
Do I need an account?
No signup is needed. Lookups go directly to the provider you configure; anonymous daily usage counts go to the project’s statistics service, and one switch in settings turns them off.
Which key should I get?
One key from either Monid or treg is enough to start. Adding both, and optionally Firecrawl, gives the waterfall more places to look. The install page compares them.
How do I keep costs under control?
There is a per-lookup cap (default $0.05) and a daily cap (default $2). Only the sender of the opened email is looked up automatically, with a daily limit you set. Results are cached, so the same address is never paid for twice. The calculator shows what a given volume would cost.
What if it shows the wrong person?
If the name from the provider doesn't match the display name in the email header, the result is marked “uncertain” and shows both names, so you can judge for yourself.
Why is a gmail.com sender not looked up?
Personal mailbox domains and role addresses like info@ rarely match a profile, so they are skipped by default to save money. Click the button in the panel to look them up anyway.
Two minutes, then it is done
The Chrome Web Store listing is not live yet, so you load the extension unpacked. Five steps, a screenshot for each.
This website may use privacy-friendly analytics to count visits. The SenderFinder extension is separate: it sends one anonymous daily usage summary unless you switch that off in its settings. Privacy
