Top "hardest level" in Geometry Dash

The term "hardest level" in Geometry Dash denotes the most challenging verified level, as determined by the collective opinion of the community. This term typically denotes the level at the #1 position on the Geometry Dash Demonlist, which is colloquially known as the Top 1 level in the modern community. This position is frequently uncertain and, as a consequence, unpredictable, as the majority of Top 1 levels only witness a small number of winners who can offer insight into the relative difficulty of their placement. Before the Demonlist was introduced, the history of Top 1 levels was primarily based on conjecture, and early Top 1 levels were frequently ranked retrospectively or as a result of disjointed community discussion.
This is a chronological list of levels that the Geometry Dash community has deemed to be the Top 1 based on collective opinions, which have been cross-checked with numerous community figures. These levels were subsequently ranked by Demonlist placement.[1]

In the event that a Top 1 level is placed below another former Top 1 level as a result of players' difficulty opinions, these levels are regarded as pseudo or fraudulent Top 1 levels, given the circumstances. The reign duration of a former Top 1 that was purportedly dethroned will be retroactively extended if they are still not Top 1 or if their reign merely persists. Nevertheless, this does not apply to levels that are not ranked as the top level but are ultimately determined to be more difficult than a former top level (e.g. Sonic Wave Infinity and Silent clubstep). This is frequently referred to as a "robbed" Top 1 by the community.

Although the majority of these levels are either unrated or deleted at present, a few have been re-verified, rated, and uploaded to the verifier's account. The default Demon rating (Hard Demon) will be used for Top 1 levels that are deleted or unrated prior to Update 2.1, as the subcategories of Demon ratings were present in the 2.1 Update. The current Top 1 is indicated in bold.
Source: geometry dash subzero