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oauth2l (pronounced "oauth tool") is a simple command-line tool for working with Google OAuth 2.0 written in Go. Its primary use is to fetch and print OAuth 2.0 access tokens, which can be used with other command-line tools and shell scripts.


oauth2l supports all Google OAuth 2.0 authentication flows for both user accounts and service accounts in different environments:

  • When running inside Google Compute Engine (GCE) and Google Kubernetes Engine (GKE), it uses the credentials of the current service account if it is available.

  • When running inside user context that has an active Google Cloud SDK (gcloud) session, it uses the current gcloud credentials.

  • When running with command option --credentials xxx, where xxx points to a JSON credential file downloaded from Google Cloud Console, oauth2l uses the file to start an OAuth session. The file can be either a service account key or an OAuth client ID.

  • When running with command option --type jwt --audience xxx and a service account key, a JWT token signed by the service account key will be generated.

  • When running with command option --type sso --email xxx, oauth2l invokes an external sso command to retrieve Single Sign-on (SSO) access token.

  • By default, retrieved tokens will be cached and stored in "~/.oauth2l". The cache location can be overridden via --cache xxx. To disable caching, set cache location to empty ("").


Pre-compiled binaries

Pre-built binaries are available for Darwin (Mac OS X), Linux, and Windows. You can download a build for any tag, for example:

OS Link

Substitute "latest" for any tag version you'd like, removing any leading "v" prefix.

Homebrew (Mac OS X)

On Mac OS X, you can install oauth2l via Homebrew:

$ brew install oauth2l

Note that new releases may not be immediately available via Homebrew because updating is a manual process.


An official Docker image is available at:

You can run this directly:

$ docker run -it header cloud-platform

Or use it to inject into an existing container:

FROM my-awesome-container
COPY --from /bin/oauth2l /bin/oauth2l

Like the binary releases, the container images are tagged to match the repository tags (without the leading "v"). For master builds, use the "latest" tag.

Everywhere else

On other systems, you need to meet the following requirements to use this tool:

Minimum requirements:

  • The tool is only available for Linux or Mac
  • Go 1.10.3 or higher

Nice to have:

# Get the package from Github
$ git clone
$ cd oauth2l

# Install the package into your $GOPATH/bin/
$ make dev

# Fetch the access token from your credentials with cloud-platform scope
$ ~/go/bin/oauth2l fetch --credentials ~/your_credentials.json --scope cloud-platform

# Or you can run if you $GOPATH/bin is already in your $PATH
$ oauth2l fetch --credentials ~/your_credentials.json --scope cloud-platform



Fetch and print an access token for the specified OAuth scopes. For example, the following command prints access token for the following OAuth2 scopes:

$ oauth2l fetch --scope,cloud-platform


The same as fetch, except the output is in HTTP header format:

$ oauth2l header --scope cloud-platform
Authorization: Bearer ya29.zyxwvutsrqpnmolkjihgfedcba

The header command is designed to be easy to use with the curl CLI. For example, the following command uses the PubSub API to list all PubSub topics.

$ curl -H "$(oauth2l header --scope pubsub)"

To send an API request using domain-wide delegation (DwD), for example, to list's Gmail labels:

$ curl -H "$(oauth2l header --email --credentials service_account_credentials.json --scope"


This is a shortcut command that fetches an access token for the specified OAuth scopes and uses the token to make a curl request (via 'usr/bin/curl' by default). Additional flags after "--" will be treated as curl flags.

$ oauth2l curl --scope cloud-platform,pubsub --url -- -i

To send an API request using domain-wide delegation (DwD), for example, to list's Gmail labels:

$ oauth2l curl --email --credentials service_account_credentials.json --scope --url


Print information about a valid token. This always includes the list of scopes and expiration time. If the token has either the or scope, it also prints the email address of the authenticated identity.

$ oauth2l info --token $(oauth2l fetch --scope pubsub)
    "expires_in": 3599,
    "scope": "",
    "email": ""


Test a token. This sets an exit code of 0 for a valid token and 1 otherwise, which can be useful in shell pipelines. It also prints the exit code.

$ oauth2l test --token ya29.zyxwvutsrqpnmolkjihgfedcba
$ echo $?
$ oauth2l test --token ya29.justkiddingmadethisoneup
$ echo $?


Reset all tokens cached locally. We cache previously retrieved tokens in the file ~/.oauth2l by default.

$ oauth2l reset


Locally deploys and launches the OAuth2l Playground web application in a browser. If the web application packages are not yet installed, it will be installed under ~/.oauth2l-web by default. See Command Options section for all supported options for the web command.

Note that a local installation of Docker and docker-compose tool is required in order to support this feature. For most platforms, Docker can be installed by following the instructions here. For Google workstations, follow special installation procedures at "go/installdocker". The web feature is currently experimental and will be improved in the future.

$ oauth2l web

Command Options


Prints help messages for the main program or a specific command.

$ oauth2l --help
$ oauth2l fetch --help


Specifies an OAuth credential file (either an OAuth client ID or a Service Account key) to start the OAuth flow. You can download the file from Google Cloud Console.

$ oauth2l fetch --credentials ~/service_account.json --scope cloud-platform

If this option is not supplied, it will be read from the environment variable GOOGLE_APPLICATION_CREDENTIALS. For more information, please read Getting started with Authentication.

$ export GOOGLE_APPLICATION_CREDENTIALS="~/service_account.json"
$ oauth2l fetch --scope cloud-platform

When using an OAuth client ID file, the following applies:

If the first redirect_uris in the --credentials client_id.json is set to urn:ietf:wg:oauth:2.0:oob, the 3LO out of band flow is activated. NOTE: 3LO out of band flow has been deprecated and will stop working entirely in Oct 2022.

If the first redirect_uris in the --credentials client_id.json is set to http://localhost[:PORT], the 3LO loopback flow is activated. When the port is omitted, an available port will be used to spin up the localhost. When a port is provided, oauth2l will attempt to use such port. If the port cannot be used, oauth2l will stop.


The authentication type. The currently supported types are "oauth", "jwt", or "sso". Defaults to "oauth".


When oauth is selected, the tool will fetch an OAuth access token through one of two different flows. If service account key is provided, 2-legged OAuth flow is performed. If OAuth Client ID is provided, 3-legged OAuth flow is performed, which requires user consent. Learn about the different types of OAuth here.

$ oauth2l fetch --type oauth --credentials ~/client_credentials.json --scope cloud-platform


When jwt is selected and the json file specified in the --credentials option is a service account key file, a JWT token signed by the service account private key will be generated. Either --audience or --scope must be specified for this option. See how to construct the audience here.

  • With audience:

    $ oauth2l fetch --type jwt --credentials ~/service_account.json --audience
  • With scope:

    $ oauth2l fetch --type jwt --credentials ~/service_account.json --scope cloud-platform


When sso is selected, the tool will use an external Single Sign-on (SSO) CLI to fetch an OAuth access token. The default SSO CLI only works with Google's corporate SSO. An email is required in addition to scope.

To use oauth2l with the default SSO CLI:

$ oauth2l header --type sso --email --scope cloud-platform

To use oauth2l with a custom SSO CLI:

$ oauth2l header --type sso --ssocli /usr/bin/sso --email --scope cloud-platform

Note: The custom SSO CLI should have the following interface:

$ /usr/bin/sso scope1 scope2


The scope(s) that will be authorized by the OAuth access token. Required for oauth and sso authentication types. When using multiple scopes, provide the the parameter as a comma-delimited list and do not include spaces. (Alternatively, multiple scopes can be specified as a space-delimited string surrounded in quotes.)

$ oauth2l fetch --scope cloud-platform,pubsub


If true, exchanges the fetched access token with an STS token using Google's Secure Token Service. You may optionally specify claims to be embedded into the STS token. The currently supported STS claims are "audience" and "quota_project".

This option is compatible with oauth and sso authentication types, but is currently incompatible with jwt.

$ oauth2l fetch --sts --audience --quota_project quotaprojectid


The single audience to include in the signed JWT token. Required for jwt authentication type. Can also be used for STS.

$ oauth2l fetch --type jwt --audience


The quota project to include in the STS claim. Used for quota and billing override.

$ oauth2l fetch --sts --quota_project quotaprojectid


The email associated with SSO. Required for sso authentication type.

$ oauth2l fetch --type sso --email --scope cloud-platform

The email parameter can be also used to specify a user email account for domain-wide delegation when authenticating with Service Account credentials.

$ oauth2l fetch --credentials ~/service_account.json --scope cloud-platform --email


Path to SSO CLI. For optional use with "sso" authentication type.

$ oauth2l fetch --type sso --ssocli /usr/bin/sso --email --scope cloud-platform


Path to token cache file. Disables caching if set to empty (""). Defaults to ~/.oauth2l if not configured.

$ oauth2l fetch --cache ~/different_path/.oauth2l --scope cloud-platform


If true, attempt to refresh expired access token (from the cache) using refresh token instead of re-authorizing.

$ oauth2l fetch --credentials ~/client_credentials.json --scope cloud-platform --refresh


If specified, exchanges the fetched User access token with a Service Account access token using Google's IAM Service. The Service Account parameter can be specified as an ID or an email. Note that at least one of "cloud-platform" or "iam" must be included in the scope parameter. Learn more about Service Account Impersonation here.

$ oauth2l fetch --credentials ~/client_credentials.json --scope cloud-platform,pubsub --impersonate-service-account 113258942105700140798


Disables the feature to automatically open the consent page in 3LO loopback flows. When this option is used, the user will be provided with a URL to manually interact with the consent page. This flag does not take any arguments. Simply add the option to disable this feature.

$ oauth2l fetch --credentials ~/client_credentials.json --disableAutoOpenConsentPage --consentPageInteractionTimeout 60 --consentPageInteractionTimeoutUnits seconds --scope cloud-platform


Amount of time to wait for a user to interact with the consent page in 3LO loopback flows. Once the time has lapsed, the localhost at the redirect_uri will no longer be available.
Its default value is 2. See --consentPageInteractionTimeoutUnits to change the units.


Units of measurement to use when --consentPageInteractionTimeout is set. Its default value is minutes. Valid inputs are seconds and minutes. This option only affects 3LO loopback flows.

fetch --output_format

Token's output format for "fetch" command. One of bare, header, json, json_compact, pretty, or refresh_token. Default is bare.

$ oauth2l fetch --output_format pretty --scope cloud-platform

curl --url

URL endpoint for curl request. Required for "curl" command.

$ oauth2l curl --scope cloud-platform --url

curl --curlcli

Path to curl CLI. For optional use with "curl" command.

$ oauth2l curl --curlcli /usr/bin/curl --type sso --email --scope cloud-platform --url

web --stop

Stops the OAuth2l Playground web app.

$ oauth2l web --stop

web --directory

Installs OAuth2l-web packages to a specfic directory. If this option is used, it should be provided again for future executions of the web command, such as stopping and restarting the web app.

$ oauth2l web --directory your/new/directory

Previous Version

The previous version of oauth2l was written in Python and it is located at the python directory. The Python version is deprecated because it depends on a legacy auth library and contains some features that are no longer best practice. Please switch to use the Go version instead.