Sound like a temp agency, ala Accenture.

Does it track market rates? I've worked for a company before that took fresh grads, and relied strongly on them never entering the market for themselves and realising what market rate was.

Yes. That's a temp agency (or an Indian consulting company but French, if you're familiar with the concept).

They're know for paying shit, and there are arrangements between agencies to not compete with each other.

Actual salaries at these places have been on a slow downward trend for many years.

Yeah, like a temp agency, but we are full employees, which means we are still paid between contracts.

The problem is knowing the market rate.

Yep, same as the company I worked for. Market rate is hard to discover, but harder still if you have an entity working against you - the company I worked for had a binding contract with any client preventing them from revealing how much they paid for temps.

Do you have a period of time you are contracted to work? If you can make friends in the Paris dev community, you might be able to find out how good/bad your pay is.

From what my former classmates told me, for profiles that are roughly equivalent, it looks like to be closer to 40k. But then they are not in consulting companies.

And I'm too much of a lazy ass to look for another job. Also I have few reason right now to seek a higher salary.

If one of those reasons is "I'm still learning", note that agency jobs can often be exactly the same as non-agency jobs, except with a middle-man sapping away a portion of salary.