No savory food available when visiting the café. And a particular staff member with red hair (Katia perhaps?) was exceptionally rude when I had my own sandwich. Even though both my partner and I had each spent £3.50 on hot drinks that were very small, about 160ml cups. I wouldn’t have even minded respectfully putting my own food away when asked, had the red headed staff member not been so offensive in her attitude. Won’t be returning. And have even noticed multiple trip advisor reviews highlighting the same particular red head staff member and her appalling conduct toward customers. Having previously managed a team in the hospitality industry, I strongly advise this individual gets retrained on the way she conducts herself and speaks to paying customers. Even more so if she happens to be the owner of this establishment. UPDATE, in response to Dimitris. “You do not make excuses for your policy on food” yet you had no food available. As stated above. I’d have respectfully put my own food away and initially did. But it then dawned on me how disgusting the manner in which your colleague spoke to a paying customer. It’s laughable that you think I was abusive. I merely made your colleague aware that her conduct was abhorrent, entitled and rude. Then she lied multiple times. To which I just repeated myself more emphatically. And you can distort the facts as much as you like. It was one and only one customer who, with no context of the situation whatsoever, decided to chime in asking me to leave it be. And as for my partner, she merely didn’t want to risk my getting stressed as I have a heart condition. But you carry on running your buisness as you do. The fact that there are numerous reviews both here and on Trip Advisor that flag the rude nature of staff at you establishment is proof enough that there something very wrong in what you consider acceptable customer service.

Very expensive. The nitro cold brew was quite bitter on its own and you are apparently not allowed any milk with it. (Please see the below issue in depth below). I was disappointed when I attended today as I was excited to try this place out, it looks fab from outside. I think going forward I will stick to my usual location of Academy, which is a shame. Myself and my flatmate went in early this morning as a treat to get some Nitro Cold Brew to take away. We never had been before and it looks fab so always wanted to try it. We asked if we could get the Nitro Cold Brew with oat milk in it as well. The server said yes that would be fine (I remember specifically, as there was initially confusion where we thought they said they didn’t think it was available but they clarified after the second server started pouring the cold brew to test the tap and the initial server said ‘oh sorry I meant I wasn’t sure if the Nitro cold brew was ready this early yet, not that you couldn’t add oat milk - that will be fine.’ So we each paid the extra 40p to have this (total on my banking app was £4.20, on the board the nitro was £3.80). However when the nitro was poured, I said to the other server whether they could please add the oat milk and they said that it doesn’t go with the cold brew and we couldn’t have it. I explained that I was confused as I thought my flatmate and I ordered it, only for the first server to turn around and explain that we actually had said we were fine with it normal and that we were confused as ‘yes it doesn’t go with the nitro cold brew.’ Therefore my flatmate and I were both disappointed but left, confused but had been convinced that maybe we had imagined it. However, we left checking our banking apps and both saying to each other that we definitely were sure we were told yes to oat milk and we were both charged for it. Therefore, it made me think the first server didn’t want to admit they were confused and changed their explanation. To top it off when we were chitchatting, I said that we managed to get up early because we were excited to go out and get food - and the first server immediately assumed it was because we were hung over - asking if we had a good night and if it was worth it. (Which I laughed off but didn’t feel it was appropriate, especially as it was incorrect). I wouldn’t normally leave such a negative review over a small thing, as usually I would have happily have drank another coffee instead without even mentioning it. However the whole interaction made me feel oddly small and doubting myself - so I thought it worth mentioning to please possibly avoid anyone else feeling this in future. Thank you.

Didn’t get a chance to try the coffee as the lady serving had such a foul attitude, we turned around and walked out. Angry looking staff member and the atmosphere felt tense. Was not warm and welcoming in the slightest.

Fantastic coffee! The best coffee in Cardiff by a mile. Can't recommend enough and the owners are always so friendly.

Really great coffee and hot chocolate - the Nitro Cold Brew is incredible and there's so many types of hot chocolate to choose from.

Mocha did not taste like a mocha at all. Not chocolatey even though they say it’s made with real chocolate. Definitely need to use more chocolate in the serving. Sizes of the drinks are ridiculous too, £3 for a very small drink. When I told the staff that my drink wasn’t up to scratch they seemed very frustrated with me and didn’t want to remake the drink. Definitely would not go back

Pretty bad coffee. Temperature was tongue-burning, destroying the milk taste. Coffee taste is bland and shallow. I’d say even Costa serves better coffee, and that’s a very low bar.

One of the best flat white and ice latte I’ve ever had! The coffee bean they’re using is more on a nutty note, perfectly roasted. The cakes were a surprise too! We ordered one lemon, chia and pistachio muffin, and a pistachio cake. Both were fragrant and there was even lemon filling inside of the muffin! The overall vibe is cosy with plenty of sunlight flashing in the place :)

What a shame that when I entered I was greeted with signs saying "laptop users: 1 hour limit, please don't treat this as your office and if you're here for longer than an hour please make another purchase". I felt very unwelcome there being greeted by those signs and left right away. I work in coffee shops on a regular basis and have never seen such a rude sign. (I can understand the reason why, but is the sign really necessary?) Won't be returning as my business doesn't feel welcome.

I really recommend it, It was my first time to visit it and it was really good . I got flat white and Crunchy caramel muffin.

My husband and I started to regularly sit in during my pregnancy rather than ordering to take away, and I now often come back with my baby whilst on maternity leave. One of the main reasons for this - aside from the great coffee - is the staff. Ruby in particular is incredibly friendly and welcoming, as is the other female member of staff with blonde hair. I feel extremely comfortable breastfeeding in there, and always have a friendly welcome (much appreciated in these early days of motherhood!). Excellent coffee and a brilliant atmosphere. Could not recommend highly enough!

Great place to go. Nice atmosphere and great service! The coffe was very good and the gluten-free cake too. I definitely recommend it if you want a nice coffe in the Bay.

Excellent coffee, a nice choice of cakes, and pleasant service. A great place!!

Lovely coffee shop. Lovely staff. Lovely coffee and lovely prices. I will be going there again next time I'm in Cardiff.

What a wonderful place! The atmosphere created by the staff makes it feel like an extension of your living room. The hot chocolate was divine, the coffee as good as you'd find in any high-end central cardiff coffee shop all set a stones throw from the bay. If your heading to the bay this summer you'd be wise to pop in for a coffee and cake!

Excellent quality coffee, all manner of choices, from nitro to macha lattes. Choice of non dairy options and nice atmosphere. Excellent location near mermaid quay, watch out for the step on entry and they don't take any cash.

What an amazing shop, I love finding indendent places like this. Top quality speciality coffee made with care by lovely positive staff. Special mention to Ruby, what a top manager they have here.

Good quality and reasonable prices - and you can find gluten free cake

I don’t mind a tiny flat white but I abhor one that tastes more of milk than coffee. Flat whites should be at least two shots and have a strong taste of coffee. Am I wrong? Disappointed coffee drinker.

Have been buying our beans here for 5yrs. Superb roast and blend. As good as coffee gets, really. Hot chocolate, the vibe, everything ... all top class.

Very nice coffee and atmosphere to do some laptop work. Very close to the bay for a nice walk after

Nice cafe just round the corner from Cardiff Bay. Friendly staff and very relaxing atmosphere. They carry a variety of beans although they are for sale and you can’t choose what your coffee is made of. On my visit the only choice for a drip (filter) coffee is from Yunnan China. Coffee was nicely brewed but a little too weak for my taste. I still enjoyed it though. It’s always nice to have freshly ground and brewed coffee.

Had a trip down to Cardiff bay for a short break and was anxious I wouldn’t be able to get my usual morning coffee fix. After a quick google, we found Quantum Coffee Roasters and decided to give it a go. Service was excellent- friendly, helpful, didn’t feel rushed or pressured. Ordering was painless, easy, and enjoyable. The atmosphere was calm and cosy. I had second thoughts about getting a take out! And, mostly importantly, the coffee was great. Really excellent. Not bitter, not sour, bang in the sweet spot. The oat milk was also steamed to the right temperature. Which quite a few coffee shops seem to get wrong and burn the milk (and my tongue!). We managed to visit twice during our stay, and both times were exactly the same. Even with different baristas on both days. Always friendly and made perfect coffee. It’s a shame that Quantum Coffee Roasters isn’t near my home!! Will definitely be visiting again the next time I’m in Cardiff bay. Couldn’t recommend highly enough.

I had a pleasant time in the cafe. Wonderful Nitro Cold Brew with delectable blueberry muffin. The overall atmosphere felt cosy and the baristas were welcoming and helpful.

Warm, friendly staff, really nice and welcoming atmosphere. We ordered two V60s that were unfortunately not well done: watery, bland, and one was more unpleasant than the other, while the other had a noticeable papery taste to it.

A pleasant place with very tasty coffee and a relaxing atmosphere. Here you can also have a healthy and nutritious breakfast.

Been using Quantum for some time, mainly ordering coffee beans online and also been into the shop in Cardiff Bay. Really like their coffee, it is priced reasonably and they are reliable. Can’t ask for any more than that really! Their shop in Cardiff Bay has a nice aesthetic and good selection of food items.

Bad customer service, disrespectful employee, worse matcha late. It’s surely my first and last time at the cafe, I ordered matcha late with oat milk and vanilla syrup all i got is oat milk with the syrup no taste of matcha at all. I asked for a refund then the old barista started shouting and talking disrespectfully.

Light and airy. Full disabled access, great staff. FANTASTIC COFFEE AND CAKES.

The red hair lady was very rude and not kind of all. My friends came from different cities in England and they agreed she was unwelcome barista. My friend love to snap new places and activities and she refused to snap the coffee when she make it and he told her he will not snap her face but she refused rudely. Also I came before 2 weeks with my family and my kids had their own food and she refused to let them eat in the coffee. The coffee was nice but the service was so bad.

Absolutely loved their Tiger Bay blend, the place itself has more of a bold style that is different than most of the coffee shops, would have loved to see more diversity in the freshly baked products.

Most enjoyable coffee I've had

Amazing coffee in the Bay - two flat whites that we haven’t been able to beat anywhere. If it’s open, don’t go anywhere else. Tried everywhere for coffee within 500m and nowhere comes close.

Good coffee. Good hot chocolate based on the intensity of cocoa. Nice place to chill out.

Open during lockdown which is always appreciated! High quality coffee and the hot chocolate menu is excellent

Got served a expensive glass of milk instead of the matcha latte I ordered. Asked politely for them to add some more matcha as advertised that would make it not just milk.Was given an attitude and wasn't offered in any way to fix it. Gave 2 stars as nothing wrong with partners drink

Decent coffee, lovely staff. Interesting industrial vibe to the decor.

Excellent fresh coffee . I'll be back

Did a search for a cafe as I would be in the area with my 14 year old reviews were great so popped In Saturdat morning, very pleased lady welcome us, ordered a Latte, Mango smoothly, the coffee "taste" was excellent, but a little disappointed as it was not hot but more like warm. I will try again as the place is very, deco was to my liking. Hopefully, I will be able to upgrade to 5 stars if my coffee is served hot next time.

Can we just talk about the kindness and friendliness at this space. Walking in for the first time, it was as if I had been going to this coffee shop for the past few weeks - I felt so welcomed and so comfortable! Pay this place a visit. The coffee and the treats were so lovely!

Over priced for what it is. The hot food selection is mostly gone and so is coke. The friendly servers have been replaced by two who clearly don't want to be there and no toilet. The selection of cakes is good and I didn't try the hot drinks so as such I award 3 stars. I came in first thing this morning Edit to reply: I can only assume you're new because you used to serve curiosity cola and lemonade. There also used to be a sign saying the customer toilet was closed and there used to be a much larger offering of hot food that wasn't packaged. The worst thing was the lack of smile from today's servers.

Found this place on a random walk past, and I'm so glad we walked in! Good coffee, great atmosphere, and a lovely place to be out of the wind and rain by the quay!

Always great service and a vast selection of drinks. Very warm atmosphere and not snooty at all like some shops. We visit every time we're in the area, and they sell their own range of beans and grounds to take home. 10/10

After Costa shut down. Started going here. I must say the Caramel Coffe is amazing here. Staff are also friendly and the atmosphere is really chilled. Some seats are really comfy too. Would love it if the coffees were a little bigger but that's just because I love them so much.

Been looking forward to going here due to the reviews. Went Sunday and was disappointed. The staff were friendly. But it was a roasting hot day and there was no air con or anything. The temp inside was so hot and uncomfortable. Ordered a v60 pour over and was sad that the coffee was bitter and not a good taste at all. And for nearly 4 pounds. Won't be going back unfortunately

In my humble opinion Quantum serve the finest coffee in Cardiff. Nice atmosphere, friendly staff/owners. Five stars from me.

One of the nicest coffee in Cardiff. Had a flat white and biscoff brownie, also had a nitro cold brew to go. All very nice! Recommended!

Coffee look good. But not what you see. Not recommend if you looking for a good coffee.

Great coffee shop, service was friendly and helpful, prices were not too much for the lovely coffee and smoothie. The leather sofa in the corner was very comfortable.