SECURITY REPORT · EXTENSHI SCAN
Costello
Chrome extension
0
/ 100 SAFETY SCORE
CAUTION
Mostly fine, but a few things worth reviewing before you install.
Automated analysis of publicly available code — not a professional security audit. It may produce false positives and does not prove an extension is unsafe or safe. Treat it as one signal among many. Disclaimer · Report an issue
How it ranks
Costello's safety score vs every other extension we've scanned
Globally
18%of extensions carry more risk
Riskier ←→ Safer
Ranked against 369,936 extensions
In Productivity
24%of productivity extensions carry more risk
Riskier ←→ Safer
Ranked against 177,133 productivity extensions
Findings
33
median 16Lower is safer
Critical findings
0
median 0Severity = Critical
Permissions
4
median 3Declared in manifest
Active users
5
median 14vs category median
Findings breakdown
Automated security signal · 33 distinct issues across 6 severities
33
distinct issues
detected
detected
Critical00%
High13%
Needs Review00%
Medium1442%
Low1545%
Info39%
Permissions requested
2 risky permissions of 4 total
2 high-risk permissions require attention
This extension requests 4 permissions in total. 2 of them grant broad capabilities that are worth a careful look.
High
View open tabs
Can see URLs and titles of all open tabs
High
Execute scripts in pages
Can inject and execute JavaScript code in web pages
Medium
Store local data
Can save data locally in the browser for persistence
Low
Use side panel
Can display content in the browser side panel
Are you the author of Costello?
Claim this extension to respond to findings, add context, and earn a verified badge on extenshi.io.
Add the badge to your README
Show Costello's live security score on GitHub or in your docs
Scan performed by extenshi.io · Aug 22, 2026
Browser extensions made transparent.