Release Plan for E-utility API Keys

As promised in our post this past spring, we are now announcing the scheduled release of API keys for the E-utilities API. If you’ve missed some of our original discussion of these keys, or have questions about how to get a key, you may want to check out this post.

In this post, we’ll be discussing three things:

  • The current status of API keys
  • Upcoming testing periods in September
  • Final public release on December 1, 2018.

So what’s the current status of keys?

At present API keys are only active in this sandbox environment:

Simply substitute any of the other E-utilities (e.g. esummary, efetch) for esearch. In this sandbox, API keys are fully active as they will eventually be on production (

  • Requests without an API key have a rate limit of 3 requests/second.
  • Requests with an API key have a default rate limit of 10 requests/second (or a higher rate limit that you’ve negotiated with us).

What are these testing periods?

In September we will be activating API keys on production for three 1-hour periods:

  • Sept 15, 6:00-7:00 PM EDT
  • Sept 20, 10:00-11:00 AM EDT
  • Sept 25, 2:00-3:00 AM EDT

During these testing periods, API keys will behave exactly as they do in the sandbox environment. Any existing key that you have will become active in production for that 1-hour period. We will be announcing each of these periods 1 day in advance on the utilities-announce mailing list.

When will API keys be fully released?

At 12:00 AM EST on December 1, 2018, API keys will become fully active in our production environment.

Want to learn more?

Please contact us at if you have questions or comments, or use this form.

Also, sign up for our webinar at 12:00 PM EDT on September 5, during which we’ll discuss this release plan and take your questions.

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