Functions

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Functions are dynamic {{ }} tokens that compute a value at send time instead of looking one up from a variable. Use them to stamp a request with a fresh UUID, the current timestamp, a Base64-encoded credential, an HMAC signature, or a value pulled from another request's response.

Where a {{variable}} resolves to a stored value, a function like {{uuid()}} runs every time the request is sent — so each send gets a new result.

Inserting a function

Type {{ in any field to open the typeahead. Below your variables it lists the available functions, grouped into sections:

The {{ typeahead, listing variables and functions

Pick a function and Rest Hippo inserts it as a highlighted pill. If the function takes arguments, the pill editor opens so you can fill them in; click an existing function pill any time to edit its arguments again.

The pill editor (for both variables and functions) shows a Live Preview of the resolved value. To copy it, double-click the preview value to select it and press Cmd/Ctrl+C, or right-click it for a Copy / Select All menu. Secret values copy as *** until you reveal them with the eye toggle.

Under the hood a function pill is just text in the form {{name("arg1", "arg2")}} — arguments are positional and double-quoted — so you can also type one by hand. {{uuid()}} takes no arguments; {{now("Unix")}} takes one.

Built-in functions

General-purpose helpers that resolve instantly, with no network or context needed.

Function	Result
`uuid()`	A random UUID v4, e.g. `9f1c…-…`. A fresh one on every send.
`now("ISO")`	The current timestamp. Format: `ISO` (default), `Unix` (seconds), `UnixMs` (milliseconds), or `RFC2822`.
`base64encode("value")`	Base64-encode the value (UTF-8 safe).
`base64decode("value")`	Base64-decode the value.
`urlEncode("value")`	Percent-encode the value for use in a URL.
`urlDecode("value")`	Percent-decode the value.
`randomInt("0", "100")`	A random integer between min and max, inclusive (defaults `0`–`100`).

Arguments can themselves contain variables — e.g. {{base64encode("{{user}}:{{pass}}")}} builds a Basic-auth credential from two variables.

Context functions

These read from where the request lives and the active environment. They take no network round-trip.

Function	Result
`collectionName()`	The name of the active collection.
`requestName()`	The name of the current request.
`environmentName()`	The name of the active environment.
`folderName("0")`	An ancestor folder's name. `0` is the immediate parent, `1` its parent, and so on.

Request Outputs

Chain requests together: pull a value out of another request's response and feed it into this one. Reference the source request by name.

Function	Result
`response("Login", ".data.token")`	A value from the named request's response body. The second argument is a dot-path (`.data.token`, `.items.[0].id`); `.` returns the whole body.
`responseHeader("Login", "Location")`	A single response header from the named request.
`responseStatus("Login")`	The HTTP status code of the named request's last response.
`run("Seed data")`	Runs the named request before this one. It produces no text of its own (it resolves to an empty string) — use it purely to trigger a prerequisite.

The dot-path is the same syntax as response captures and works over JSON, YAML, or XML bodies.

Refresh mode

response, responseHeader, and responseStatus each have a Refresh mode:

Use last result (default) — read the value from the source request's most recent response, without re-sending it. Fast, but the source must have been run at least once.
Run immediately before — send the source request first, every time, then read from its fresh response. Use this when the value is short-lived (e.g. a one-time token) and must be current on every send.

Backend functions

These run in Rest Hippo's main process (where the crypto and OS APIs live) and resolve asynchronously.

Function	Result
`hmac("SHA256", "key", "message")`	An HMAC signature. Algorithm: `SHA256` (default) or `SHA512`.
`hash("SHA256", "value")`	A hash of the value. Algorithm: `SHA256` (default) or `SHA512`.
`environmentVariable("RESTHIPPO_API_KEY")`	An OS environment variable. For safety, only names beginning with `RESTHIPPO_` are readable — any other name returns empty, and the prefix is not stripped.

environmentVariable lets you keep a secret out of your stored collection entirely: export RESTHIPPO_API_KEY=… in your shell before launching Rest Hippo, then reference it with {{environmentVariable("RESTHIPPO_API_KEY")}}.

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