Looking for the more working class or grittier areas of Paris, St Denis?

If you mean the street of St Denis, I would not consider that area to be "gritty" at all. In fact, it's teeming with tiny restaurants that you can't get into with a shoehorn.

Saint Denis - outside the periphery of Paris - might be called "gritty" by some, but is really a working class neighbourhood. Probably most people would not want their photos taken there.

There are outdoor markets in every neighbourhood in Paris except on Monday. Google "marches volants" and you'll get the whole list. Note that most vendors do not like to be photographed.

Little children may not be photographed without their parents' permission.

If you go to a cafe to take photos, some people will view it as an invasion of privacy.

If you plan on going to the Bois de Boulogne you can take lots of landscape photos - but better be sure that you don't catch prostitutes at work.

There is a lot of art sprayed on the walls of buildings. Google to find the best spots.

Butte Aux Cailles is supposed to be "gritty." Not sure of that, but I did take some great photos. It's not such a commercial area, and there are a few amazing little restaurants. It's in the 14th behind Place d'Italie.

Butte Aux Cailles is not gritty at all; it is more boho than anything else. Much of the 19th would fit this classification; it is also full of really great street art.

Hey Stew - I'm building a map of spots with good street art and graffiti for an upcoming trip
I'm seeing good things out in Pantin. .

How about the areas around Gare de l'Est and Gare du Nord? Or the Metro stop "Blanche" If you are not used to them, you might find them gritty, even though tons of tourists pass through there in the summer. North Americans are a very small number, if at all, among these swarms of tourists.

While not regarded as "gritty" by those of us who live there, a tourist might find working class areas north and east of the metro#2 fitting that description. This takes in the 18th-20th and part of the 12th. As this is a big area, you can obtain information by googling by topic or metro stop. As these are not tourist areas, and include many different cultures, you will have to be sensitive as to whether or not you should photograph people, religious observations, and other activities. You will be quickly spotted as an "outlander" and should adjust your behavior accordingly.

Thanks all.

Craigo, Pantin sounds interesting. I figure the locals will know I am not of the area. I like a change from the usual Paris highlights.
Père Lachaise Cemetery area is more working class.

I like to see these area before they become gentrified, check out family run restaurants, markets and such.

I remember a hostel in Budapest that was up a dark alley and there was this local bar nearby that maybe had seating for 10. that was cool sitting in there

"Pere Lachaise cemetary is more working class"

Except most of the residents are no longer working.

I recommend the 11th arrondissement. Some of that area is getting a bit hip. I spent a day walking around there, searching for some of the hot coffee shops (I did find one but the name is escaping me right now). I did go to a high spot in Paris, not sure where, but I had read about it in an online article. I walked up and up and found a lovely small park with a good view over Paris. It was in or near the 11th. perhaps search for high elevation point in Paris and you too may find it. Great tiny streets and walkways. It was outlined in my map book too.

David Lebovitz (chef) recommends the Barbes market which is multicultural and could be overwhelming with the jostling. A bit tamer is the Aligre market. He has a website and did just post about this on FB a day or 2 ago. I find the food markets farther from the centre are pretty cool.

I visited the Commerce market in the 15th, so a bit tonier, but a lovely market with none or very few tourists.

I stayed in the lower 5th a couple of times, near rue Mouffetard and visited place d'Italie in the 13th, which not gritty is more regular people world. when staying on rue Claude Bernard, we breakfasted with the locals at plain old cafe on the same street, with the old dudes hanging at the bar sipping coffee (and maybe wine), some students and older couples meeting for a coffee. It was a nice environment. We definitely were the only tourists at breakfast.

I would say just roam farther and farther from the centre and see what you can see.

Enjoy Paris, I am counting the days until I will be there! June

My graffiti walk was years ago in the 19th and things change with that, but the larger pieces are still there and there is a lot of new stuff. https://wordpress.com/post/janettravels.wordpress.com/461
The map link I used is no longer current, but there are lots of commercial walks you can pay for and a lot of on line sources like this one:
https://streetart360.net/2017/03/19/street-art-in-paris-the-ultimate-guide/

We visited St Denis Cathedral which is worth the trip out (end of that Metro line I think). We started to look around the shopping area but decided to head back to the Metro. The area was sketchy and unappealing. Maybe Canal St Martin would interest you--we did not find it worth the effort either.