UnseenEmail trackers Unseen blocks
Updated November 14, 2026: 184 companies, 332 patterns.
Unseen checks the address of every image in the emails you open in Gmail against these patterns. They come from the open-source Simplify and Trocker blocklists. Unseen also blocks hidden and 1×1 images from companies that aren't on the list, so the list is a floor, not a ceiling.
Want to know which trackers are in a particular email? Use the email tracker checker.
Add Unseen to Chrome, free Also for Firefox
| Company | Patterns |
|---|---|
| 365offers.trade | 1 |
| Absolutesoftware-email | 1 |
| Acoustic | 1 |
| ActionKit | 1 |
| Active | 1 |
| ActiveCampaign | 1 |
| Adobe | 5 |
| AgileCRM | 1 |
| Airbnb | 1 |
| AirMiles.ca | 1 |
| Alaska Airlines | 3 |
| Amazon | 7 |
| Amazon SES | 1 |
| Apple | 2 |
| Appriver | 1 |
| Apptivo | 1 |
| Asus | 1 |
| AWeber | 1 |
| Axios | 1 |
| BananaTag | 2 |
| Blueshift | 2 |
| Bombcom | 1 |
| BoomerangGmail | 1 |
| Boots | 1 |
| Boxbe | 1 |
| Browserstack | 1 |
| BuzzStream | 1 |
| CampaignMonitor | 1 |
| CanaryMail.io | 1 |
| CirrusInsight | 2 |
| Clio | 1 |
| Close.io | 2 |
| Cloudhq.io | 2 |
| Coda.io | 1 |
| CodePen.io | 1 |
| ConneQuityMailer | 1 |
| Constant Contact | 2 |
| ConstantContact | 2 |
| ContactMonkey | 1 |
| ConvertKit | 2 |
| Copper | 1 |
| Cprpt | 1 |
| Creditmantri | 1 |
| Critical Impact | 1 |
| Customer.io | 3 |
| Dell | 1 |
| DidTheyReadIt | 1 |
| DotDigital | 2 |
| Driftem | 1 |
| Dropbox | 1 |
| DZone | 1 |
| Ebsta | 3 |
| EdgeSuite | 1 |
| Egocdn | 1 |
| Email tracker | 6 |
| EmailTracker.website | 1 |
| Emarsys | 1 |
| Etransmail | 1 |
| EventBrite | 1 |
| EventsInYourArea | 1 |
| EveryAction | 1 |
| Evite | 2 |
| 3 | |
| Flipkart | 1 |
| ForMirror | 1 |
| FreeLancer | 1 |
| FreshMail | 2 |
| FrontApp | 2 |
| FullContact | 1 |
| GearBest | 1 |
| Gem | 1 |
| GetBase | 1 |
| GetMailSpring | 1 |
| GetNotify | 1 |
| GetPocket | 1 |
| GetResponse | 1 |
| Github | 1 |
| GlassDoor | 1 |
| Gmass | 4 |
| Gmelius | 1 |
| 3 | |
| Grammarly | 1 |
| Granicus | 1 |
| GreenMailInc | 1 |
| GrowthDot | 1 |
| Homeaway | 1 |
| HubSpot | 4 |
| HubSpot Sales | 51 |
| Hunter.io | 1 |
| IBM Marketing Cloud | 1 |
| iContact | 2 |
| Infusionsoft | 2 |
| Insightly | 1 |
| Intercom | 2 |
| Is-tracking-pixel-api-prod.appspot | 1 |
| JangoMail | 1 |
| Klaviyo | 1 |
| LaunchBit | 1 |
| 1 | |
| Litmus | 1 |
| LogDNA | 1 |
| Magento | 3 |
| MailButler.io | 1 |
| Mailcastr | 1 |
| MailChimp | 4 |
| MailCoral | 1 |
| MailGun | 1 |
| MailInifinity | 1 |
| MailJet | 2 |
| MailTag.io | 1 |
| Mailtrack | 1 |
| MailTrack.io | 2 |
| Mailzter.in | 1 |
| MandrillApp | 2 |
| Marketo | 2 |
| Mention | 1 |
| MetaData.io | 1 |
| MixMax | 4 |
| MixPanel | 1 |
| MyEmma | 2 |
| Nation Builder | 2 |
| NeteCart | 1 |
| Nethunt | 2 |
| NewtonHQ | 1 |
| OpenBracket.co | 1 |
| Opicle | 1 |
| Oracle | 6 |
| Outreach.io | 4 |
| PayBack.in | 2 |
| PayPal | 1 |
| Paytm | 2 |
| phpList | 2 |
| PipeDrive | 2 |
| Playdom | 1 |
| Polymail.io | 2 |
| PostmarkApp | 1 |
| ProductHunt | 1 |
| ProlificMail | 1 |
| Quora | 1 |
| ReplyCal | 1 |
| ReplyMsg | 1 |
| Responder.co.il | 1 |
| Return Path | 1 |
| Rocketbolt | 1 |
| Runtastic | 1 |
| Sailthru | 1 |
| Salesforce | 6 |
| Salesforce Marketing Cloud | 1 |
| SalesHandy | 1 |
| SalesLoft | 1 |
| Segment | 1 |
| Selligent | 1 |
| Sendgrid | 6 |
| SendInBlue | 2 |
| SendPulse.email | 1 |
| Sendy.co | 1 |
| Signal.co | 1 |
| Skillsoft | 1 |
| Streak | 2 |
| StrongView | 1 |
| Substack | 1 |
| Super Human | 1 |
| TataDocomoBusiness | 1 |
| Techgig | 1 |
| TheAtlantic | 1 |
| TheTopInbox | 1 |
| Thunderhead | 1 |
| TinyLetter | 1 |
| ToutApp | 1 |
| TrackApp.io | 3 |
| Transferwise | 1 |
| Trello | 2 |
| Udacity | 1 |
| Unknown | 5 |
| Unsplash | 1 |
| Upwork | 1 |
| Vcommission | 1 |
| Vtiger | 1 |
| WildApricot | 2 |
| Wix | 1 |
| Workona | 1 |
| Yamm | 1 |
| YesWare | 4 |
| Zendesk | 1 |
Missing a tracker? Tell us on GitHub.