These are answers to the most frequently asked questions about Cambridge Dictionaries Online. If you have a question which isn't in this list, or if the answer given does not satisfy you, please This email address is being protected from spambots. You need JavaScript enabled to view it. with your question.

How can I start using the API?

You need to register, if you haven't already. When we've approved your registration, we'll email you an API evaluation key, which you can use to try out the API on the demo page and in your development environment. When you decide you want to start using the API in an application or website, You need to get an API key by going to the Request API key page and filling in the form (you will first need to register, if you haven't done so already). If we approve your proposed use of the API, we'll send you an agreement to sign, and then an API key.

Can I access a demo for testing the API?

Yes, once you've been given an API key, you'll be able to use it on the demo page. Here, you can try out all the different methods and datasets, and see what the output data looks like in all available formats.

Can I use my evaluation key in an application?

No, you need to request an application key. Each application should have a separate key.

Where does the key go in an API request?

The API key should be sent in the header of the HTTP request as the accessKey value.

What formats are available?

The response may be sent as JSON or XML. Set your HTTP request Accept header to application/json or application/xml to select the response format. The default is JSON. The content of the entries themselves may be sent as HTML5 or XML. This is controlled by the format parameter in the request URL, which should have the value html or xml.

Do you have bindings for my language?

We have bindings/wrappers for in several languages which do the job of making HTTP requests:

  • Java
  • Javascript
  • Objective-C
  • Perl
  • PHP

Let us know if you are using another language: we may already be working on a binding which we can share with you.

A method call returns an error!

Make sure you're using the base HTTPS url Here are some possible messages

  • 403 Forbidden: You need to use a valid access key.
  • 404 Not Found: The response content should contain an errorCode and errorMessage which explain the problem.
  • NoResults: The term you're looking for can't be found in the dictionary you're looking in.
  • InvalidPath: The method URL you've provided isn't correct.

What are the costs/subscription prices?

We will send a commercial agreement for you to sign when you request an API application key. An outline of what is contained in the commercial agreement.

What are the terms of use?

The terms of use can be found here. You will need to read and agree to the terms of use before registering and receiving an API evaluation key.

Why don't the ordinary terms allow me to store data?

We log information on requests to measure how our dictionaries are being used. This information helps us improve our data and also helps us identify when data is being misused. If you store the data and retrieve it from an intermediary location, this interferes with this.

How can my users make use of the API without sharing the key with them?

We recommend that your server makes the API requests and formats and hands over the results to your users.

I have users who need data offline / I would like to perform research with your data

If you're interested in storing data, e.g. for research purposes, or for embedding in devices with limited connectivity, we can negotiate a license for this. You should consider how long you will use the data, what you need it for, and, if you are distributing it, how you plan to ensure users only use it for the intended purpose.

What do the Cambridge Dictionaries data sets contain?

As well as headwords and definitions, we show derived words, phrases, idioms, and phrasal verbs; we mark collocations in examples, include irregular inflections and grammar information and provide audio and written (IPA) pronunciations. Information on the coverage and target level of the dictionaries is available from the Cambridge Dictionaries Online website:

I have found a word that is not in the dictionary!

No dictionary is complete. Highly-specialised fields have their own vocabulary, and technological change means some of these words come and go very quickly. We use a corpus containing billions of words of real English to determine what the most important words are.

Are your dictionaries just for learners?

We have found that many native speakers of English appreciate the clear definitions and useful examples in our dictionaries, and we know that the Cambridge Dictionaries Online website is used by native speakers and learners of English alike.

Are your dictionaries suitable for students/children?

The Learner's and American dictionaries have been written with a school environment in mind. However, schools have many different expectations of learning materials. If you want to know more about the coverage of particular areas, we suggest you browse the dictionaries on Cambridge Dictionaries Online.