John Musser founded ProgrammableWeb in 2005, and for more than a decade it was the directory of public APIs — the place you went to find out what existed, to track the growth of the space, and to understand the emerging API economy. It grew from a few hundred listings into thousands and was the closest thing the early API world had to a central record of itself. It chronicled the movement, not just the endpoints.
It shut down in 2022. Two things killed it, and both are structural rather than particular to that site.
Manual curation does not scale against a space growing faster than humans can catalog it, and the quality of a directory decays quietly as listings go stale — the API is gone, the docs moved, the company was acquired — long before anyone notices.
And the economics never worked. A directory creates enormous value for the ecosystem and captures very little of it. That is exactly the incentive problem underneath API discovery generally.
The lesson I took, and the reason I built APIs.json, is that a sustainable index has to be generated from what providers publish about themselves rather than assembled by hand by a third party. That architecture is still right. Getting providers to publish remains the hard part.
