Dynamic variables

Dynamic variables are built-in placeholders that Nouto replaces with a generated value each time you send a request. They need no environment setup. Type {{$ in the URL bar, a key-value table, or the body editor to browse them in autocomplete.

For environment variables, response values, and cookies, see Variable substitution.

Syntax

A dynamic variable starts with $, followed by a namespace, a dot, and a method name. Arguments follow the name, separated by commas:

{{$uuid.v4}}
{{$random.int, 1, 100}}
{{$hash.sha256, my-value}}

Nouto trims spaces around each argument and reads arguments as literal text. This has three consequences:

• An argument can’t contain a comma, because commas separate arguments.
• An argument can’t contain }, because }} ends the placeholder. For example, {{$json.minify, {"a": 1}}} doesn’t resolve.
• A {{variable}} inside the arguments isn’t resolved first. For example, {{$encode.base64, {{USERNAME}}}} doesn’t encode the value of USERNAME. To send Base64-encoded credentials, use the Basic auth type instead.

If Nouto can’t produce a value, for example because the method name is misspelled or a required argument is missing, it sends the placeholder unchanged.

UUID

Variable	Output
{{$uuid.v4}}	Random UUID version 4, for example 550e8400-e29b-41d4-a716-446655440000
{{$uuid.v7}}	UUID version 7. The first 48 bits hold the current time in milliseconds, so values sort by creation time.

Timestamps

Variable	Output
{{$timestamp.unix}}	Current time in seconds since the Unix epoch, for example 1706886400
{{$timestamp.millis}}	Current time in milliseconds since the Unix epoch, for example 1706886400000
{{$timestamp.iso}}	Current time in ISO 8601 format, in UTC, for example 2024-02-02T12:00:00.000Z
{{$timestamp.offset, amount, unit}}	Unix seconds offset from now. {{$timestamp.offset, 30, m}} is 30 minutes from now, and {{$timestamp.offset, -1, d}} is one day ago.
{{$timestamp.format, format}}	Current local time in a custom format, for example {{$timestamp.format, YYYY-MM-DD}} gives 2024-02-02

The offset units are s (seconds), m (minutes), h (hours), and d (days). The unit defaults to s.

The format tokens are YYYY (year), MM (month), DD (day), HH (hour, 24-hour clock), mm (minute), and ss (second). Without a format argument, Nouto uses YYYY-MM-DDTHH:mm:ss. The output uses your computer’s time zone.

Random values

Variable	Output
{{$random.int}}	Whole number from 0 to 1000
{{$random.int, min, max}}	Whole number from min to max, inclusive
{{$random.number, min, max}}	Number between min and max. If either bound has a decimal part, the result has two decimal places, for example {{$random.number, 0.5, 9.5}} gives 4.73. Otherwise the result is a whole number. Defaults to 0 and 1000.
{{$random.string}}	16 random letters and digits, for example aB3kR9mPqX2wNv7L
{{$random.string, length}}	Random letters and digits of the given length, from 1 to 256
{{$random.bool}}	true or false
{{$random.enum, a, b, c}}	One of the listed values, for example {{$random.enum, dev, staging, prod}}
{{$random.name}}	First and last name, for example Jennifer Garcia
{{$random.email}}	Email address at example.com, example.org, or test.com, for example jennifer.garcia482@example.com

Hashes and HMAC

Hash variables take the input text as the first argument and return a lowercase hex string:

Variable	Algorithm
{{$hash.md5, input}}	MD5
{{$hash.sha1, input}}	SHA-1
{{$hash.sha256, input}}	SHA-256
{{$hash.sha512, input}}	SHA-512

HMAC variables take the input text and a key, and also return a lowercase hex string:

Variable	Algorithm
{{$hmac.md5, input, key}}	HMAC-MD5
{{$hmac.sha1, input, key}}	HMAC-SHA1
{{$hmac.sha256, input, key}}	HMAC-SHA256
{{$hmac.sha512, input, key}}	HMAC-SHA512

Both arguments are literal text, so you can’t pass the request body or an environment variable as the input or key. See Syntax.

Encoding and decoding

Variable	Output
{{$encode.base64, input}}	Base64
{{$encode.base64url, input}}	URL-safe Base64 without = padding
{{$encode.url, input}}	Percent-encoded text, for example hello world becomes hello%20world
{{$encode.html, input}}	HTML entities for &, <, >, ", ', and characters outside ASCII
{{$decode.base64, input}}	Decoded Base64 or URL-safe Base64
{{$decode.url, input}}	Decoded percent-encoding

Regex and JSON

Variable	Output
{{$regex.match, input, pattern, flags}}	First match of pattern in input, or an empty string if nothing matches. flags is optional, for example i.
{{$regex.replace, input, pattern, replacement, flags}}	input with matches of pattern replaced. Pass g as flags to replace every match.
{{$json.escape, input}}	input escaped for use inside a JSON string, without surrounding quotes
{{$json.minify, input}}	input parsed as JSON and printed without whitespace

Patterns follow JavaScript regular expression syntax. Because arguments can’t contain , or }, quantifiers such as \d{3} don’t work in a pattern. The same rule means $json.minify can’t receive a JSON object.

Fake data

The $faker namespace generates realistic test data with the Faker library. Every value is new on each send. The tables below list every $faker method. Methods with arguments show their defaults.

Person

Variable	Example output
{{$faker.firstName}}	Martin
{{$faker.lastName}}	Lind-Kuvalis
{{$faker.fullName}}	Katie Schneider
{{$faker.jobTitle}}	Senior Response Agent
{{$faker.gender}}	Female
{{$faker.prefix}}	Ms.
{{$faker.suffix}}	DVM

Internet

Variable	Example output
{{$faker.email}}	Danyka75@gmail.com
{{$faker.username}}	Jacky.Bednar45
{{$faker.url}}	https://limited-tributary.name/
{{$faker.domainName}}	key-sand.net
{{$faker.ip}}	52.112.253.111
{{$faker.ipv6}}	a8a8:ca6c:697e:8af9:d3a9:9db9:02fb:fff1
{{$faker.mac}}	49:3f:fd:7d:24:7b
{{$faker.password, length}}	R5u2yF7d1KrY0Q2s (length defaults to 16)
{{$faker.userAgent}}	Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) ...

Location

Variable	Example output
{{$faker.city}}	Shaynachester
{{$faker.state}}	Arizona
{{$faker.country}}	Sierra Leone
{{$faker.countryCode}}	UY
{{$faker.street}}	Boyle Extension
{{$faker.streetAddress}}	347 Chestnut Street
{{$faker.zipCode}}	03845-7870
{{$faker.latitude}}	-2.9453
{{$faker.longitude}}	-28.7075
{{$faker.timeZone}}	America/Yakutat

Phone and company

Variable	Example output
{{$faker.phone}}	1-588-410-5542 x54927
{{$faker.company}}	Shields - Fay
{{$faker.catchPhrase}}	Persevering cohesive product
{{$faker.buzzPhrase}}	orchestrate compelling convergence

Finance

Variable	Example output
{{$faker.amount, min, max, decimals}}	993.88 (defaults to 0, 1000, and 2)
{{$faker.currencyCode}}	TRY
{{$faker.currencyName}}	Kwanza
{{$faker.iban}}	LV57UZHEX486O08000615
{{$faker.creditCard}}	4208-9478-6802-2199
{{$faker.bitcoinAddress}}	15mqbwxjJacmncVQ7neshvVoDAK4KWBh

Lorem text

Variable	Example output
{{$faker.word}}	arx
{{$faker.words, count}}	aliqua ad turpis (count defaults to 3)
{{$faker.sentence}}	Spargo decretum terror vito compello solus defero.
{{$faker.paragraph}}	Three Lorem sentences
{{$faker.slug}}	adversus-conduco-officia

Strings and identifiers

Variable	Example output
{{$faker.uuid}}	2d948a4d-6ed1-4a4c-a87e-0850c8e95f10
{{$faker.nanoid}}	ZZc4f5csT_m9lfOf_F_kd
{{$faker.alpha, length}}	tsTrUHrd (length defaults to 8)
{{$faker.alphanumeric, length}}	fYp9iTaM (length defaults to 8)
{{$faker.numeric, length}}	19509375 (length defaults to 8)
{{$faker.hexadecimal, length}}	0xFd9B9BCF (length defaults to 8, not counting the 0x prefix)
{{$faker.boolean}}	true

Dates

Variable	Example output
{{$faker.past}}	ISO 8601 date within the past year, for example 2026-09-25T03:47:13.911Z
{{$faker.future}}	ISO 8601 date within the next year, for example 2026-11-13T08:40:29.486Z
{{$faker.recent}}	ISO 8601 date within the past day, for example 2026-10-04T19:10:37.979Z
{{$faker.birthdate}}	1979-02-25
{{$faker.weekday}}	Monday
{{$faker.month}}	April

Colors and images

Variable	Example output
{{$faker.colorName}}	yellow
{{$faker.colorHex}}	#ac28ad
{{$faker.colorRgb}}	rgb(170, 205, 112)
{{$faker.imageUrl}}	https://picsum.photos/seed/Syeu3n/549/788
{{$faker.avatar}}	https://avatars.githubusercontent.com/u/47297999

Hacker, database, and system

Variable	Example output
{{$faker.hackerPhrase}}	I'll bypass the back-end SSL hard drive, that should transmitter the IB sensor!
{{$faker.hackerAbbr}}	THX
{{$faker.dbColumn}}	password
{{$faker.dbType}}	enum
{{$faker.dbEngine}}	MyISAM
{{$faker.fileName}}	till_brook_where.jsonld
{{$faker.fileExt}}	html
{{$faker.mimeType}}	application/epub+zip
{{$faker.semver}}	6.3.7

Prompt for a value at send time

Use {{$prompt.name}} for a value you want to type each time you send, such as a one-time code. Replace name with a label of your choice. The label can’t contain spaces, commas, or }.

{
  "username": "{{username}}",
  "otp": "{{$prompt.otp}}"
}

When you send the request, Nouto scans the URL, query parameters, headers, body, GraphQL variables, and the username, password, token, and API key fields of the Auth tab. If it finds $prompt placeholders, it opens an Enter values dialog with one field per label. A label used several times gets one field.

• Click Send in the dialog to send the request with the values you entered.
• Click Cancel to stop. Nouto doesn’t send the request.

Nouto uses the values for that one send and doesn’t save them. The Collection Runner doesn’t prompt, so it sends {{$prompt.name}} unchanged.

Read a file at send time

Use {{$file.read, path}} to insert the text content of a file when you send the request. Use an absolute path:

Authorization: Bearer {{$file.read, /home/user/.secrets/token.txt}}

The file is read as UTF-8 text, and its full content replaces the placeholder, including any trailing newline. If the file can’t be read, for example because it doesn’t exist, Nouto sends the placeholder unchanged.

Note

$file.read resolves in the VS Code extension. In the desktop app and the Collection Runner, Nouto sends the placeholder unchanged.

Examples

These examples combine several dynamic variables in one request.

Generate test data for a user creation request:

{
  "id": "{{$uuid.v4}}",
  "name": "{{$faker.fullName}}",
  "email": "{{$faker.email}}",
  "role": "{{$random.enum, admin, editor, viewer}}",
  "createdAt": "{{$timestamp.iso}}"
}

Send a token that expires in one hour:

{
  "issued_at": {{$timestamp.unix}},
  "expires_at": {{$timestamp.offset, 1, h}}
}

Send a unique idempotency key with each request:

Idempotency-Key: {{$uuid.v7}}