The STF, a public funder based in Germany, has launched a "challenge" funding program to encourage developers who use and rely on FOSS infrastructure software projects to contribute back with security improvements, documentation or developer tooling. These relatively shorter duration (4 months with another potential 4 month renewal) contributions are meant to complement their main funding program which targets maintainers for longer term support. Participants in this "challenge" can ask for up to 300k in Euros to fund their work.