The HTTP Lookup Variable for the Google Tag Manager server container lets you make an HTTP request (GET, POST, or PUT) to any URL and use the response as a variable value anywhere in your container — as raw text, a full parsed JSON object, or a single key extracted from it.
Features
- Any HTTP method: GET, POST, or PUT.
- JSON or Form-Data payloads: build the request body as a nested JSON object (dot notation), a flat JSON object, or a URL-encoded form body.
- Custom headers: attach any additional request headers, overriding the defaults if needed.
- Response parsing: return the raw response body, the full parsed JSON object, or a specific key from it (dot notation supported, e.g.
foo.bar.0.id). - Built-in caching: store responses in Template Storage with a configurable expiration time, to save requests and reduce latency.
- Redirect following:
301/302responses are automatically followed. - Configurable timeout: set a custom request timeout.
How to Use
- Add the HTTP Lookup variable to your GTM Server container from the Template Gallery or by importing the template file.
- Set the Request Method (GET, POST, or PUT) and the Destination URL.
- For POST/PUT requests, choose the Request Type (JSON or Form-Data) and add key/value pairs under Request Data:
- Use dot notation in a key (e.g.
user.id) to build a nested JSON object, or enable Do not use dot notation to keep the key literal. - Enable Put request object inside an array to wrap the payload in a JSON array.
- Use dot notation in a key (e.g.
- Optionally add custom Request Headers.
- Enable Parse response as JSON to get a JSON object instead of a raw string, and optionally enable Extract key from JSON object to return a specific value (supports dot notation, e.g.
data.items.0.id). - Enable Store response in cache to cache identical requests in Template Storage (see Response Caching below).
- Optionally set a custom Request Timeout under Additional Options.
Response Caching
When Store response in cache is enabled, the response is cached in Template Storage, keyed by the request (URL, method, headers, body, and the configured JSON key name). Only responses with a 2xx status code are cached — a failing endpoint never gets “stuck” serving a cached error.
The Cache Expiration Time field (in hours) controls how long a cached response is reused before a fresh request is made. Leaving it empty means the cache never expires on its own — it’s only invalidated when the request itself changes, or the template version is upgraded.
Useful Resources
Open Source
HTTP Lookup Variable for GTM Server Side is developed and maintained by Stape Team under the Apache 2.0 license.
