What is the difference between a URI and a URL?

A URI identifies a resource. A URL is a kind of URI that also tells you where the resource is and how to reach it. https://example.com/pricing is a URL. Every URL is a URI, but not every URI is a URL.

A URN is a URI that names something with a permanent identifier instead of a location. urn:isbn:9780141036144 identifies one book, but it does not tell your computer where to download it.

Are API endpoints URIs or URLs?

Both. https://api.example.com/customers/123?details=true identifies a customer record and tells you where to send the request, so it is a URL, and every URL is a URI. Most docs use "endpoint", "API URL" and "URI" interchangeably.

Does it matter which word I use in a Clay or n8n workflow?

Not for the tool. What matters is that the value is a complete address with a scheme, like https://. Most "invalid URL" errors come from a missing scheme, a stray space or an unencoded character, not from the word you used.

What is a redirect URI?

It is the address an app sends people back to after they approve a login, for example when you connect Google or HubSpot to a tool. The provider only accepts addresses you registered in advance, so a mismatch in the scheme, path or trailing slash fails the connection.

Why do people say URL for everything?

Because in web work nearly every address you touch is a URL. The current web standards also use the word URL for the whole family. The URI versus URL distinction mostly shows up in older specifications, API documentation and OAuth settings.

Learn GTM & Sales Automation URI vs URL

Fundamentals

URI vs URL: the one distinction GTM docs keep assuming you know

API docs say "endpoint URI", OAuth screens ask for a "redirect URI", and your tracking links are URLs. They are related, and the difference takes about four minutes to learn.

5 parts of a URL 5 places it shows up ~4 min read

A URI (Uniform Resource Identifier) identifies a thing. A URL (Uniform Resource Locator) is a URI that also tells you where the thing is and how to get it.

Every URL is a URI, but not every URI is a URL.

Think of a person's name versus their home address. The name identifies them. The address tells you where to find them. A URL is the address version, and it is the one you meet ninety-nine times out of a hundred.

The family

URI, URL, URN and relative references

A URI is the parent. URLs and URNs are two ways of being one.

URI
├── URL  identifies + tells you where and how to fetch it
│   └── https://example.com/users/123
│
└── URN  identifies by a permanent name, no location
    └── urn:isbn:9780141036144

Kind	Example	Identifies?	Locates?
URL	`https://example.com/pricing`	Yes	Yes, and says how to fetch it
URN	`urn:isbn:9780141036144`	Yes, by a permanent name	No
Relative reference	`/customers/123`	Only next to a base address	Only next to a base address

The ISBN is the classic example of a URN. It pins down exactly one book without saying which shop or server has it.

Anatomy

What is inside a URL

Take one address from an API call and split it up. Each part matters to a different piece of your stack.

https://api.example.com/customers/123?utm_source=email&details=true#pricing

Scheme

https

How to talk to the server. An http:// link in a cold email can trigger a browser warning, so check what your tracking domain serves.

Host

api.example.com

Where the resource lives. Custom tracking domains and subdomains change this part and nothing else.

Path

/customers/123

Which resource on that host. In an API call, the 123 is usually the record ID you are fetching.

Query

?utm_source=email&details=true

Labels and options. This is where UTM tags live, and where an HTTP column in Clay passes its parameters.

Fragment

#pricing

A spot inside the page. The browser keeps it and never sends it to the server, so it will not show up in server-side tracking.

So is an API endpoint a URI or a URL?

Both. The address https://api.example.com/customers/123?details=true identifies a customer record, and it tells you where to send the request. That makes it a URL, and every URL is a URI.

This is why docs mix the words freely: "endpoint URL", "API URL", "base URI". You will not break anything by using either. If a doc asks for one, paste the full address including https://.

Where the word shows up in GTM work

Five places you are likely to see "URI" and what to do about each one.

1

A field in Clay or Airtable is labeled "URI"

Almost always a full web address. Treat it as a URL unless the docs say otherwise.
2

An API doc says "base URI" or "endpoint URI"

The address you send requests to. Same thing as an endpoint URL.
3

A webhook needs a "redirect URI"

The address the tool sends the user back to after login. It has to match what you registered exactly, down to the trailing slash.
4

A link in your email template starts with /

A relative reference. It works on your website and breaks in an inbox, because there is no site for it to be relative to.
5

A CRM stores mailto: or tel: values

Valid URIs that identify an action, not a page. Do not run them through a "is this URL live" check.

Why everyone just says URL

On the web, nearly every address is a URL, so the shorter, friendlier word won. We say URL parameters, URL routing and the URL bar. The current web standards use "URL" for the whole family too.

The stricter split still appears in older specs, API docs and OAuth settings. When you see "URI" there, read it as "the address", then check whether it needs to be a full one or can be relative.

Common questions

FAQ: URI vs URL

Keep going

More GTM and sales automation breakdowns, built the same way.

GTM & Sales Automation → ← All resources