Authentication

The Sentinel Hub API uses OAuth2 Authentication and requires that you have an access token. In essence, this is a piece of information you add to your requests so the server knows it's you. These tokens do not last forever for a multitude of reasons, but you can get new ones and when they expire from the Sentinel-Hub OAuth2 server at the token endpoint listed below. But first, if you do not have one already, you need to register an OAuth Client in your account settings. This is so the server can expect you to make such token requests. If you do not have a Sentinel-Hub account, you can sign up for a free trial account.

How to use tokens

Once you have a token, do use it for authenticating all your requests within its validity period. While tokens do not last forever, they do last a reasonable amount of time, and sufficiently long that they can be reused. The information of how long each token lasts is embedded in the token itself in the exp claim, and can be read from there.

Do not fetch a new token for each API request you make. Token requests are rate limited, so if you are getting an HTTP 429 error, that means you are requesting too many tokens.

Tokens are JSON Web Tokens (JWT), more information about them here or here.

Registering OAuth client

To register an OAuth client, open the "User Settings" tab in your dashboard, then click the Create new button (1) in the "OAuth client" section. Give your OAuth client a name (2), set the Client grant type to Client Credentials, and click the Create client button (3). Your client secret will be displayed. Copy the secret value (4) and paste it locally, as it will not be visible after the pop-up window closes! When you are finished, click Close (5). You should now see the newly created OAuth client name and ID (6) in the list of your OAuth clients. With client ID and client secret, you are now ready to request tokens.

To request tokens the easiest way is to have some software which understands OAuth2 and can make the proper request. For example, REST clients like Postman and Insomnia have support for OAuth2 Client credentials already included. See the Token Request Examples section below.

OAuth2 Endpoints

Token Endpoint - for requesting tokens

https://services.sentinel-hub.com/oauth/token

Token info endpoint

https://services.sentinel-hub.com/oauth/tokeninfo

Token Request Examples

cURL

The following cURL request will return an access token, just make sure to replace <your client id> with your client ID and <your client secret> with your client secret:

curl --request POST --url https://services.sentinel-hub.com/oauth/token --header "content-type: application/x-www-form-urlencoded" --data "grant_type=client_credentials&client_id=<your client id>" --data-urlencode "client_secret=<your client secret>"

Postman

In the Postman request Authorization tab set the Type to OAuth 2.0 and Add the authorization data to Request Headers. Then click the Get New Access Token button. Set the Grant Type to Client Credentials, the access token URL to the token endpoint, then set the Client ID and Client Secret to the values of your OAuth Client. Scope can be blank. Keep Client Authentication as Send As Basic Auth Header. Click Request Token. You should get a new one immediately. To use this token to authorize your request, click Use Token. For more information see the Postman authorization documentation

Python

In python the requests-oauthlib library can handle the retrieval of access tokens using your OAuth Client configuration.

from oauthlib.oauth2 import BackendApplicationClient
from requests_oauthlib import OAuth2Session

# Your client credentials
client_id = '<client_id>'
client_secret = '<secret>'

# Create a session
client = BackendApplicationClient(client_id=client_id)
oauth = OAuth2Session(client=client)

# Get token for the session
token = oauth.fetch_token(token_url='https://services.sentinel-hub.com/oauth/token',
                          client_secret=client_secret)

# All requests using this session will have an access token automatically added
resp = oauth.get("https://services.sentinel-hub.com/oauth/tokeninfo")
print(resp.content)

requests-oauthlib doesn't check for status before checking if the response is ok. In case there's a server error, the user can receive an incorrect error, which falsely makes it seem as if the issue is on client side. Library's compliance hooks will prevent the invalid status response from being ignored, returning the correct error. To use them, add the following code:

def sentinelhub_compliance_hook(response):
    response.raise_for_status()
    return response

oauth.register_compliance_hook("access_token_response", sentinelhub_compliance_hook)

Javascript

Example using axios.

import axios from "axios"
import qs from "qs"

const client_id = "<client_id>"
const client_secret = "<secret>"

const instance = axios.create({
  baseURL: "https://services.sentinel-hub.com"
})

const config = {
  headers: {
    'Content-Type': 'application/x-www-form-urlencoded;charset=utf-8'
  }
}

const body = qs.stringify({
  client_id,
  client_secret,
  grant_type: "client_credentials"
})


// All requests using this instance will have an access token automatically added
instance.post("/oauth/token", body, config).then(resp => {
  Object.assign(instance.defaults, {headers: {authorization: `Bearer ${resp.data.access_token}`}})
})

reCAPTCHA Based Authentication

With public web-applications, there is always a risk that someone will hijack the API credentials (e.g., OGC instance ID or Processing API OAuth client ID/secret) and misuse them for their own purposes. We have worked around this by integrating Google reCAPTCHA technology, which allows for anonymous token authentication. We are using this technology in our web applications (e.g. EO Browser) and it is also available to our Enterprise-level users.

To implement it into your application, follow the instructions below.

Register your reCAPTCHA keys here: reCAPTCHA v3.
You will receive a reCAPTCHA site key and secret key.
Put the site key you received into your application (as an example, see line 29 in SentinelPlayground/tokenAssisted.html).
Register an OAuth client, select IMPLICIT grant type and fill in Redirect URL for your application.
Contact us and provide us the generated client_id of your OAuth client and the reCAPTCHA secret key. The secret key is required so that the backend can verify the captcha.
After we receive needed information, we will update your client_id configuration to support the anonymous authentication.
You can now configure it in your application as seen in line 25 of the example SentinelPlayground/tokenAssisted.html.

Note that as with any other security measure, things can be broken. However, we have found this option to be quite secure. You can, of course, implement another method of hiding credentials on your side.