From Netflix’s Stu­dio & Con­tent Engi­neer­ing team:

Polly.JS is a stand­alone, frame­work-agnos­tic JavaScript library that enables record­ing, replay­ing, and stub­bing of HTTP inter­ac­tions. By tap­ping into mul­ti­ple request APIs across both Node & the brows­er, Polly.JS is able to mock requests and respons­es with lit­tle to no con­fig­u­ra­tion while giv­ing you the abil­i­ty to take full con­trol of each request with a sim­ple, pow­er­ful, and intu­itive API.