API "Hello World" code

Question

The Stack Exchange API is based on HTTP and URLs, just like the web page you're browsing now. Except instead of HTML, the responses are all in JSON.

Let's say we wanted to call the /info method:

https://api.stackexchange.com/2.2/info?site=stackoverflow&key=app key

• 2.2 - the current api version
• info - the method
• site=site name - the site to query
• key=app key - a parameter to pass to the method

The response:

{
    "items": [
        {
            "api_revision": "2014.1.3.9409",
            "total_questions": 6381965,
            "total_unanswered": 1490184,
            "total_accepted": 3767695,
            "total_answers": 11393820,
            "questions_per_minute": 2.24,
            "answers_per_minute": 3.99,
            "total_comments": 29151387,
            "total_votes": 41269191,
            "total_badges": 8166497,
            "badges_per_minute": 2.86,
            "total_users": 2684447,
            "new_active_users": 23
        }
    ],
    "quota_remaining": 299,
    "quota_max": 300,
    "has_more": false
}

(For a full list of possible API methods, refer to the documentation.)

Do I need an API key?

A single IP address can only make a limited number of requests per day to the API. This limit is determined at by the presence of an API key. Should an IP address be using more than one key, the highest request limit will be used.

API daily limits:

• Key: 10,000
• No Key: 300

The No Key limit is meant to facilitate experimentation, not for deployed apps.

Requests with invalid or revoked keys are not stepped down to the No Key limit; they just aren't completed.

For further discussion of keys, refer to How API Keys Work.

---

Register for an API Key

---

How do I announce my application, library, wrapper, or userscript?

Create a question here and tag it app, library, or script.

Please refer to How to list your application/library/wrapper/script here for suggested formatting.

Answer 1

Protip: when working with any API that returns JSON, install the JSONView Firefox Extension.

By default, Firefox wants to download the application/json content type. This is not very helpful. JSONView changes the behavior so that you view the JSON in the browser, and additionally get syntax highlighting and expand/collapse.

Answer 2

Python:

Below is python code to get minimal info results. See bottom on how to run.

import requests

BASEURL = "https://api.stackexchange.com/2.2/info"

params = {
  "site" : "stackoverflow"
  }

r = requests.get(BASEURL, params=params)

print(r.json())

Expected output is like:

{u'has_more': False,
 u'items': [{u'answers_per_minute': 4.68,
   u'api_revision': u'2017.1.3.24329',
   u'badges_per_minute': 4.74,
   u'new_active_users': 14,
   u'questions_per_minute': 2.95,
   u'total_accepted': 7109267,
   u'total_answers': 20764568,
   u'total_badges': 21064205,
   u'total_comments': 64348720,
   u'total_questions': 13084294,
   u'total_unanswered': 3663230,
   u'total_users': 6546678,
   u'total_votes': 93817071}],
 u'quota_max': 300,
 u'quota_remaining': 299}

You can paste the code into a jupyter notebook cell and run, or put the code into a file stack-api.py and run from terminal or command line with python stack-api.py.

Answer 3

JavaScript:

Here is a bare-bones javascript, and you can run it from the console of decent modern browsers. It returns the 5 most recently active economics questions, tagged inflation:

fetch (
    'https://api.stackexchange.com/2.2/questions?pagesize=5&tagged=inflation&site=economics'
)
.then (function (response) {
    if (response.ok) { return response.json(); }
} )
.then (rJsn => console.log (rJsn) );

It returns rJsn as an object like:

{ items: Array[5], has_more: true, quota_max: 300, quota_remaining: 288 }

where rJsn.items is the payload and is like:

[
    {
        "tags": ["inflation"],
        "owner": { "display_name": "Bob Umadbro" },
        "view_count": 408,
        "answer_count": 3,
        "score": 6,
        "last_activity_date": 1488986618,
        "creation_date": 1449974376,
        "question_id": 9767,
        "title": "Inflation without Increase in Money Supply?",
        ...
    }, {
        "tags": ["inflation", "growth", "money-supply"],
        "owner": { "display_name": "gabyarg25" },
        "view_count": 91,
        "answer_count": 1,
        "score": 4,
        "last_activity_date": 1488804578,
        "creation_date": 1483498408,
        "question_id": 14897,
        "title": "What happens if money supply grows more slowly than inflation?",
        ...
    },
    ...
]

---

---

A more robust starter example:

fetch (
    'https://api.stackexchange.com/2.2/questions?pagesize=5&order=desc&sort=activity&tagged=inflation&site=economics&filter=!Pvz4gBt9fuC8jI)sZ7Hbtli6RDBLFE'
)
.then (function (response) {
    if (response.ok) {
        return response.json();
    }
    throw new Error (`API problem: Error ${response.status}, ${response.statusText}`);
} )
.then (function (rJsn) {
    if (rJsn.backoff  ||  rJsn.error_id) {
        throw new Error (`From API: Backoff ${rJsn.backoff}, Error: ${rJsn.error_id}, ${rJsn.error_message}, ${rJsn.error_name}`);
    }
    console.log (`Quota remaining: ${rJsn.quota_remaining}; Items found: ${rJsn.items.length}`);

    let zQuestions = rJsn.items;
    console.log ("\nQuestion Titles\n---------------");
    for (let qst of zQuestions) {
        console.log (qst.title);
    }
} );

Note:

1. Always check for error codes and responses!
2. Always check for the backoff value! If present you do not need to error-out though. Your code can wait the indicated interval and try again.
3. Monitor quota_remaining. When it gets to 0, you are done for the day.
4. API key not shown. Just add &key=YOUR_API_KEY to the fetch URL.
5. Use a filter every time.
6. For lots of results, monitor has_more and keep fetching the next page as necessary.