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When building apps with Interval, it's helpful to understand the boundaries of how and where code is being executed. We've created a hybrid architecture under which business logic and secrets live within your infrastructure and the rendering of interfaces for your tools is handled through Interval.

By example, let's step through this simple app which imports the Interval SDK, written in a JavaScript codebase:

const path = require("path");
const { Interval } = require("@interval/sdk");
const databaseClient = require("./db");

const interval = new Interval({
apiKey: "<YOUR API KEY>",
routesDirectory: path.resolve(__dirname, "routes"),

const { Action } = require("@interval/sdk");

module.exports = new Action(async io => {
const userId = await io.input.number("Enter a user id");

const user = await databaseClient.user.findById(userId);

return {
greeting: `Hello, ${}`,

This action is defined within your own codebase. @interval/sdk is imported just like any other package.

When interval.listen() is called, we establish a persistent bi-directional message passing link between your app and Interval.

Of course, it's a little more involved than this under the hood, but to a first approximation, the Interval SDK exists to:

  • Set up a message passing link w/ Interval
  • Parse and act on messages from Interval
  • Create and send messages to Interval

So what are these messages?

The first message sent over this link tells Interval, "here's the list of the actions my app can handle."

  1. From your app -> Interval:


From within the Interval web dashboard, when someone at your company clicks "run" on the "hello_user" action, Interval sends a message to your app, saying, "start executing the "hello_user" action.

  1. From Interval -> your app:


The interval client you defined then calls the function you named hello_user. When await io.input.number("Enter a user id") is called, the Interval SDK sends a message saying, "Collect data of type number from the user running the action".

  1. From your app -> Interval:

REQUEST_INPUT('number', { label: 'Enter a user id' })

The Interval dashboard will present the user running the action with an input to enter a number. When they complete entering their input, Interval sends a message back to your app saying, "here's the input you asked for."

  1. From Interval -> your app:

INPUT_PROVIDED('number', { value: 123 })

Because Interval is rendering interfaces, collecting input and displaying output on your app's behalf through our io methods, Interval does see the data passed to/from those methods, but it is never stored or logged on our systems.

Once the function has finished executing, your app then emits a message to Interval saying, "the action has completed."

  1. From your app -> Interval:


I/O methods

I/O methods provide an easy way to reason about what Interval can and cannot see in the context of a function running. Unless you're explicitly calling an I/O method inside of your action, Interval has no information about what code is being executed.

Input/output data passed to/from I/O methods is strictly transient by default. Under our default configuration, we never log or otherwise store this data.

This highlights an important security property of Interval actions: your business logic lives in your codebase and is executed exclusively on your infrastructure. Interval is structurally designed so that it needs to know as little as possible.


Interval's hybrid architecture allows us to develop robust and always up-to-date interfaces for your tools while keeping your most sensitive information like business logic and secrets within your infrastructure.

Below is a quick reference table you can refer to which sums up the boundaries of this architecture:

Visible to Interval?
Names of actionsYes
Action state (running, returned, etc. )Yes
Source code / business logic of ActionsNo
Environment information (secrets, etc.)No
inputs/outputs for `io` methodsYes
Logged or persisted by Interval?
Names of actionsYes
Action state (running, returned, etc. )Yes
Source code / business logic of ActionsN/A
Environment information (secrets, etc.)N/A
inputs/outputs for `io` methodsNo, by default. Opt-in optionally.

What data does Interval store?

By default, Interval stores transaction logs and return values to provide audit logging for your account. We also track SDK method usage for analytics purposes, but we never log or store the data associated with those SDK calls.

Contact us at to discuss custom retention settings.

Interval's infrastructure is hosted on DigitalOcean in the SFO3 region. All data stored on Interval is encrypted at rest with LUKS and in transit with SSL.

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