How an API request works
For a web API, your client sends an HTTP request to an endpoint. The URL identifies a resource, the method states the intended action and headers carry details such as authentication and response format.
GET /v1/products/42 HTTP/1.1
Host: api.example.com
Authorization: Bearer TOKEN
Accept: application/json
HTTP/1.1 200 OK
Content-Type: application/json
{"id":42,"name":"Desk lamp","price":29.99}The server validates the request, performs the action and returns a status code plus a body, often formatted as JSON. The API documentation defines available endpoints, required fields and authentication rules.
Not every API uses the web. Libraries, operating systems and databases also expose APIs, but data collection workflows usually use web APIs.
API vs web scraping
| API | Web scraping | |
|---|---|---|
| Source | Documented endpoint | Public web pages |
| Data format | Usually structured JSON or XML | HTML that must be extracted |
| Access controls | Keys, scopes and quotas | Site rules and crawler controls |
| Change risk | Version changes or deprecation | Layout and markup changes |
Use an official API when it provides the data you need under acceptable terms. Web scraping can collect public information that an API omits, but your crawler must follow the site’s terms, robots.txt directives and request limits.
APIs in data collection
A reliable API client usually needs to handle:
- Authentication: send an API key, OAuth token or signed request as documented.
- Pagination: follow page numbers, cursors or continuation tokens until the result set ends.
- Rate limits: stay within the service’s requests-per-minute or account quotas.
- Errors: retry temporary failures but stop on invalid credentials or malformed requests.
When rate limiting produces a 429 Too Many Requests response, honor Retry-After when present and reduce your request rate.
Using a proxy with an API
An HTTP client can send API traffic through a proxy by setting its proxy URL to http://USERNAME:PASSWORD@HOST:PORT. The proxy changes the source IP seen by the API, which can support location testing or centralized network egress.
A proxy doesn’t change your API key, permissions or account-based quota. Rotating IPs to evade an API limit may violate its terms and often won’t work because limits can follow the account or token. If the proxy rejects its credentials, it returns 407 Proxy Authentication Required before the request reaches the API.
FAQ
What does API stand for?
API stands for Application Programming Interface. It describes the rules software follows to request data or functionality from another component or service.
Is an API better than web scraping?
Usually, if an official API provides the required data. APIs return predictable fields, while scraping is useful when permitted public data is available only in web pages.
Can I use a rotating proxy with an API?
Yes, if the API permits proxy traffic. Rotation can disrupt IP allowlists or IP-bound sessions, and it doesn’t reset limits attached to your API key or account.