  We present the use of grounding airbridge arrays to trim the frequency of
microwave coplanar-waveguide (CPW) resonators post fabrication. This method is
compatible with the fabrication steps of conventional CPW airbridges and
crossovers and increases device yield by allowing compensation of design and
fabrication uncertainty with $100~\mathrm{MHz}$ range and $10~\mathrm{MHz}$
resolution. We showcase two applications in circuit QED. The first is
elimination of frequency crowding between resonators intended to readout
different transmons by frequency-division multiplexing. The second is frequency
matching of readout and Purcell-filter resonator pairs. Combining this matching
with transmon frequency trimming by laser annealing reliably achieves fast and
high-fidelity readout across 17-transmon quantum processors.
