this has happened a few times lately where it's taken me a moment to describe what I do - it's only a small thing but I just kinda want to get it right as I live in paris and it comes up a lot

essentially I do writing for NGOs, startups, and creative agencies, working on anything from advertisements, to reports, to blogs

'copywriter' or 'writer' captures it well in english, what's the best way to say this in french?