A consent management platform is the software that shows the banner, records the decision and exposes a signal your tags can read. The category runs from a free plugin to an enterprise contract, and the difference between them is much less about the banner than about what happens to the record afterwards. That is also the part that is hardest to evaluate from a pricing page.
What it actually does
Three jobs. It renders the interface, in the regions and languages you configure. It stores the decision, with whatever detail it chooses to keep. And it publishes a signal, usually into the page or the tag manager, that other code can read before firing. A platform can be excellent at the first and useless at the second, which is the common shape of the cheap end of the market.
The four questions worth asking
Can I export every consent record, with its categories and its timestamp, in a format I can read without your product. Does the record say which version of the banner text was on screen. How does the signal reach my tag manager, and what happens to tags that do not read it. And what does the platform itself store on the visitor's device, including any analytics of its own. The last question surprises vendors more often than it should.
What it will not do
It will not find your tags. It will not decide which category each one belongs in. It will not stop a tag that nobody rewired to wait for the signal, which means a platform installed on a site whose tag manager was never touched changes nothing at all. Every one of those is the site owner's work, and a platform bought in the expectation that it replaces them produces an expensive banner that does not gate anything.
Scanning, and how much to trust it
Most platforms include a scanner that crawls the site and proposes categories. It is a good starting inventory and a poor final answer: it misses interaction-triggered tags, pages behind a login and anything on a page type it did not reach, and it categorises from a vendor database that is right often enough to be trusted and wrong often enough to matter. Use it for coverage, then check its output by hand on your important page types.
When you do not need one
A site that sets nothing beyond a session cookie needs no platform and no banner, and saying so plainly is better than installing a box that claims otherwise. A site with a handful of tags and a competent tag manager can often do this with the manager's own consent facilities plus a durable record of its own. The platform earns its money when you have many domains, several regions, or an obligation to produce records you can stand behind.
Questions people ask about consent management platform
Is a free CMP good enough?
For the interface, often. Check what it keeps: many free tiers store a single flag and offer no export, which is exactly the part you will need later.
Do I still need one if I use a tag manager?
Not necessarily. The manager can carry the signal. What you still need is a durable, readable record of the decisions, and that is usually what a platform is really being bought for.
Will a CMP make me compliant?
No. It gives you the means. The gating and the categorisation are decisions somebody at your company has to make and verify.
What should I check first after installing one?
That nothing non-essential is written on a fresh visit before a choice is made. If that fails, nothing else about the platform matters yet.