1. A method comprising: receiving, by a web browser of a computing device that has hardware implementing a particular instruction set architecture, a native code module that includes untrusted binary code native instructions for the particular instruction set architecture; loading, by a loader included in the web browser on the computing device, the native code module into a memory of the computing device; validating, by a validator included in the web browser on the computing device, the untrusted binary code native instructions in the native code module when the native code module is loaded in the memory by: performing a decoding traversal, by the validator on the computing device, of all executable instructions in the native code module; and determining, by the validator on the computing device, that the decoded traversed executable instructions in the native code module are compliant with a plurality of security requirements for the particular instruction set architecture; and executing the untrusted binary code native instructions directly on the hardware of the computing device and in a secure runtime environment that is included in the web browser, after validating the untrusted binary code native instructions.