> ## Documentation Index
> Fetch the complete documentation index at: https://docs.stackone.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Connect PubChem with NCBI API Key – StackOne Hub

> Link a PubChem account in the StackOne Hub using NCBI API Key. End-user guide to authorize the integration and start using PubChem actions.

## Create your NCBI API key

This connection type needs a key, but using it is optional: the **No Authentication** option works without one. PubChem's own services (PUG REST, PUG View, autocomplete and RDF) take no keys and ignore it. Only the Entrez actions, which call NCBI's E-utilities, send it: NCBI allows **3 requests/second** per IP address without a key and **10 requests/second** with one. Follow the steps below to create a key in your NCBI account and add it in StackOne Hub.

**1. Sign in to your NCBI account**

Open the [NCBI account login page](https://account.ncbi.nlm.nih.gov/) and sign in. NCBI does not use a password of its own. Pick one of the third-party login methods on the **Log in** screen:

<ul>
  <li>**eRA Commons**</li>
  <li>**Google Account**</li>
  <li>**ORCiD**</li>
  <li>**Login.gov**</li>
  <li>**Microsoft**</li>
  <li>**NIH Account**</li>
  <li>**NCBI Account**</li>
  <li>If you do not yet have an NCBI account, use **more login options** or **Sign up** to create one first.</li>
</ul>

![NCBI Log in screen showing the available third-party login methods](https://mintcdn.com/stackone-60/ts9AC_SsZJsKIdk_/connectors/pubchem/images/apikey-config-sign-in.png?fit=max\&auto=format\&n=ts9AC_SsZJsKIdk_\&q=85\&s=be440712fd881b43d23767c29958ebbb)

**2. Open Account settings**

Once signed in, click your profile email at the top right, then select **Account settings** from the dropdown menu. You can also open the [NCBI account settings page](https://account.ncbi.nlm.nih.gov/settings/) directly.

![NCBI My NCBI dashboard with the ACCOUNT dropdown open (from the profile email at the top right) and Account settings highlighted](https://mintcdn.com/stackone-60/ts9AC_SsZJsKIdk_/connectors/pubchem/images/apikey-config-account-settings.png?fit=max\&auto=format\&n=ts9AC_SsZJsKIdk_\&q=85\&s=cc78fbca6199d8623339e197aec5896d)

**3. Create or copy your API key**

Scroll down to the **API Key Management** section. If you have no key yet, click **Create API Key** and NCBI generates a single key for your account. If a key already exists there is no **Create API Key** button. The existing key is shown in the **API Key** row, so copy that one.

<ul>
  <li>NCBI states: *E-utils users are allowed 3 requests/second without an API key. Create an API key to increase your e-utils limit to 10 requests/second.*</li>
  <li>**Only one API Key per user.** Replacing or deleting it makes the current key inactive.</li>
  <li>StackOne sends the key as the `api_key` request parameter for you.</li>
</ul>

![API Key Management section of NCBI Account settings with the Create API Key button highlighted](https://mintcdn.com/stackone-60/ts9AC_SsZJsKIdk_/connectors/pubchem/images/apikey-config-create-api-key.png?fit=max\&auto=format\&n=ts9AC_SsZJsKIdk_\&q=85\&s=9416d275a9f588a58ef6a7c6be8e9af4)

**4. Copy your API key into StackOne Hub**

After you click **Create API Key**, the message **API key successfully created.** appears and your key is shown in the **API Key** row. Copy it and paste it into the **API Key** field in StackOne Hub.

<ul>
  <li>**API Key** is required for this connection.</li>
  <li>**Contact Email** is optional. NCBI uses it to contact you before throttling heavy usage.</li>
  <li>Your key stays available in **API Key Management**. Return there any time to copy it again, replace it or remove it.</li>
</ul>

![API Key Management section after key creation, with the generated key redacted and the Copy your API key location highlighted](https://mintcdn.com/stackone-60/ts9AC_SsZJsKIdk_/connectors/pubchem/images/apikey-config-copy-api-key.png?fit=max\&auto=format\&n=ts9AC_SsZJsKIdk_\&q=85\&s=e108af1ed6f8a48ba8b09271299542a1)

## Linking the Account from the Hub

**1. Navigate to the Hub**

Use one of the three [Linking Account Methods](https://docs.stackone.com/connect/managing-connectors/linking-accounts.md) to access the Hub.

**2. Fill out the fields**

Fill out the following fields using details from your provider:

<ul>
  <li>**API Key**</li>
  <li>**Contact Email** (Optional)</li>
</ul>

**3. Connect**

<ul>
  <li>Click **Connect**</li>
  <li>If applicable, the provider will redirect you to a sign-in or authorization page. Complete the provider's authorization flow.</li>
  <li>Once authorization is successful, you will see a confirmation popup</li>
</ul>

If the account linking is successful, you will see the newly linked account on your [Accounts](https://app.stackone.com/accounts) page.


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