OTFR

Short for “on the for real”. Frequently used immediately preceding or following a sincere compliment in writing (via comments, forum, text, etc) which could easily be misinterpreted as disingenuous or sarcastic. Informs the recipient(s) that the statement (or question) should be taken literally; no need to evaluate whether they’re being tooled like a chump. Identical meaning as “OTR” but distinct in that it’s “spelled out” with the inclusion of “f” to convey the intended authenticity, with the bonus of implying/indicating you’re aware of vernacular which existed prior to the invention of the fleshlight.

Conversational use of the longer format “on the for real?” as an exclamation, synonymous with “are you serious?, expressing legit amazement or incredulity when presented with unexpected information, dates back at least to the late 1980s.

When I saw your accomplishment I was inspired to complete work on my own project, and attempt a similarly high level of quality to what you’ve produced here. OTFR.

Or...
How were you able to accomplish such a positive outcome in only the given period of time? OTFR