  Blazars are known for their energetic multiwavelength flares from radio
wavelengths to high-energy $\gamma$-rays. In this work, we study radio,
optical, and $\gamma$-ray light curves of 145 bright blazars spanning up to
8~yr, to probe the flaring activity and interband correlations. Of these, 105
show $>1\sigma$ correlations between one or more wavebands, 26 of which have a
$>3\sigma$ correlation in at least one wavelength pair, as measured by the
discrete correlation function. The most common and strongest correlations are
found between the optical and $\gamma$-ray bands, with fluctuations
simultaneous within our $\sim 30$~d resolution. The radio response is usually
substantially delayed with respect to the other wavelengths with median time
lags of $\sim 100$--160~d. A systematic flare identification via Bayesian block
analysis provides us with a first uniform sample of flares in the three bands,
allowing us to characterise the relative rates of multiband and "orphan"
flares. Multiband flares tend to have higher amplitudes than "orphan" flares.
