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    0.6.4 • Public • Published

    Secure EcmaScript (SES)

    Build Status dependency status dev dependency status License

    Secure EcmaScript (SES) is a frozen environment for running EcmaScript (Javascript) 'strict' mode programs with no ambient authority in their global scope, and with the addition of a safe two-argument evaluator (SES.confine(code, endowments)). By freezing everything accessible from the global scope, it removes programs abilities to interfere with each other, and thus enables isolated evaluation of arbitrary code.

    It runs atop an ES6-compliant platform, enabling safe interaction of mutually-suspicious code, using object-capability -style programming.

    See to see how SES fits into the various flavors of confined EcmaScript execution. And visit for a demo.

    Derived from the Caja project, .

    Still under development: do not use for production systems yet, there are known security holes that need to be closed.

    Incorporates (as a dependency) the Realms shim, which is a TC39 proposal spec here: .


    npm install npm run build

    Run the test suite

    npm test

    Bug Disclosure

    Please help us practice coordinated security bug disclosure, by using the instructions in to report security-sensitive bugs privately.

    For non-security bugs, please use the regular Issues page.


    npm i ses@0.6.4





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    • warner
    • kriskowal
    • erights
    • dckc
    • michaelfig