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Early-time observations of Type Ia supernovae (SNe Ia) are essential toconstrain their progenitor properties. In this paper, we present high-qualitylight curves of 127 SNe Ia discovered by the Zwicky Transient Facility (ZTF) in2018. We describe our method to perform forced point spread function (PSF)photometry, which can be applied to other types of extragalactic transients.With a planned cadence of six observations per night ($3g+3r$), all of the 127SNe Ia are detected in both $g$ and $r$ band more than 10\,d (in the restframe) prior to the epoch of $g$-band maximum light. The redshifts of theseobjects range from $z=0.0181$ to 0.165; the median redshift is 0.074. Among the127 SNe, 50 are detected at least 14\,d prior to maximum light (in the restframe), with a subset of 9 objects being detected more than 17\,d before$g$-band peak. This is the largest sample of young SNe Ia collected to date; itcan be used to study the shape and color evolution of the rising light curvesin unprecedented detail. We discuss six peculiar events in this sample,including one 02cx-like event ZTF18abclfee (SN\,2018crl), one Ia-CSM SNZTF18aaykjei (SN\,2018cxk), and four objects with possible super-Chandrasekharmass progenitors: ZTF18abhpgje (SN\,2018eul), ZTF18abdpvnd (SN\,2018dvf),ZTF18aawpcel (SN\,2018cir) and ZTF18abddmrf (SN\,2018dsx).

ZTF Early Observations of Type Ia Supernovae I: Properties of the 2018 Sample