Do you want to make money online without paying anything? Then I say, it is not possible without paying anything.
Why?
For making money online you have to invest either money or effort. If you invest both, you will get success very soon. If you have no money to invest, then choose the second: effort. So why you need to be skilled in a specific profession or service you can offer through online, it may be freelancing marketplace, blog or website.

Make Money Online Without Paying Anything
Here are the effective 5 ways to make money online without paying money but effort:
  1. Freelancing at Marketplace:

    'Freelancing' is the most known terms in ONLINE who are seeking for the job here. If you have any specific skill to serve others, you can join any freelancing marketplace and will be paid for doing jobs. Upwork, Freelancer, Fiverr, PeoplePerHour are the most popular of them. You can serve anything with your skill. Fiverr is the best choice for the beginners. 
  2. Blogging at Blogger(Service):

    Blogging is the smartest way to make money as well as promoting yourself. If you don't have any budget, you can start blogging on Blogger (a blogging service by Google). Here, you don't need to purchase domain & hosting. Monetizing a blog is very simple. Putting ads, affiliate links, promoting other paid post etc are the effective way to monetize. Read to know 5 ways to make money from blogging.
  3. Publishing Video Content on Youtube:

    Nowadays, uploading video contents & publishing on Youtube has become trendy & the most effective way to be popular. Many of Youtube has become a celebrity overnight through it. If you think you can do anything before the camera, don't wait to promote yourself. You can also do the interesting video of anything which may be enjoyable or helpful for others. Not only that, you can easily earn $1000/Month from your videos by monetizing your Youtube channel.
  4. Selling photos/videos:

    Yes, you are listening to the truth. Now it is the great income source by selling photos, footage clips, illustrations, vectors are designed or created by you. If you are a photographer, video content creator, graphics designer this way can be effective & successful.  Alamy, iStockPhoto, SutterStock, Photoshelter etc may be the right choice to sell photos or video clips.
  5. Selling products on Facebook:

    Many entrepreneurs have been succeeded their startup online business on Facebook. You don't need website even any budget to boost your post if your facebook page has a lot of organic followers/likers. Just promote your facebook post of the specific product with more clearly and eye-catchy. 
So if you are serious to make money online without paying anything but efforts, you should start with one of the above.