I’m sorry, but I do not “know” what is the “rendering the JSON” (I’m noob create videogames and I don’t speak I very good English). The screen I record is the Unity preview screen (the camera) if you mean that with the output on the web
It’s always good to state which technologies you’re using, otherwise it’s guesswork for those who are trying to help you. Since you mentioned Unity now, I’m assuming you may be using Tiled2Unity or SuperTiled2Unity. In that case, the problem you’re having may be covered on the following page:
Extruding/padding your tiles is also mentioned there like @the-simian did in his talk, and if you want to use non-integer scaling factors and place your map at sub-pixel positions, this would be the way to avoid those lines.
However if you just do that the pixels will keep this slight “jittering”, so the preferred way to avoid it in my opinion is to use an integer zoom factor and round the map’s position such that it’s always aligned to physical pixels.
Bjorn just said most of what I would have followed up with. Just to clarify what I meant by ‘rendering the JSON’. Tiled as an editor is agnostic as to what consumes its output. You can make a map in Tiled and load it into many things, and the output is often times JSON. In your case, Unity is the engine that is consuming Tiled’s output and managing rendering. In my talk I linked, it’s a web framework called Phaser.
As Bjorn mentioned, the tile padding (or tile extruding) as a concept can apply to anything, not just Phaser as is in my talk. Judging from the way the lines (artifacts) look, my bet is that is still what is causing your issue.