Chmod Calculator API

Convert chmod permissions between octal (755) and symbolic (rwxr-xr-x) online. Handles setuid, setgid and sticky bits — free and instant.

The Chmod Calculator is also available as a free REST API. Send a POST request with a JSON body to https://dot.tools/api/tools/chmod-calc — no authentication, no API key, CORS enabled. Successful calls return { "ok": true, "result": { … } }; failures return HTTP 400 or 422 with an error body.

Request body

Field	Type	Required	Description
`octal`	string	optional	Octal permission value: 3 or 4 digits (0-7), optional leading zero. Examples: 755, 0644, 4755.
`symbolic`	string	optional	Symbolic permission string: 9 characters (rwxrwxrwx with s/S/t/T substitutions), or a 10-character ls -l string with a leading file-type character.

Response

Field	Type	Required	Description
`octal`	unknown	required	Octal representation, 3 digits or 4 when special bits are set.
`symbolic`	unknown	required	9-character symbolic representation with s/S/t/T for special bits.
`bits`	unknown	required	Special permission bits.
`error`	unknown	required	Error message when the input could not be converted.

Example request

curl -X POST https://dot.tools/api/tools/chmod-calc \
  -H 'Content-Type: application/json' \
  -d '{
  "octal": "4755"
}'

Sample response

{
  "ok": true,
  "result": {
    "octal": "4755",
    "symbolic": "rwsr-xr-x",
    "bits": {
      "setuid": true,
      "setgid": false,
      "sticky": false
    },
    "error": null
  }
}

Use the free Chmod Calculator in your browser, read the Chmod Calculator guide, or import the full OpenAPI specification.