  A public release of slitless spectra, obtained with ACS/WFC and the G800L
grism, is presented. Spectra were automatically extracted in a uniform way from
153 archival fields (or "associations") distributed across the two Galactic
caps, covering all observations to 2008. The ACS G800L grism provides a
wavelength range of 0.55-1.00 \mu$m, with a dispersion of $40 \ \AA / pixel$
and a resolution of $\sim 80\ \AA$ for point-like sources. The ACS G800L images
and matched direct images were reduced with an automatic pipeline that handles
all steps from archive retrieval, alignment and astrometric calibration, direct
image combination, catalogue generation, spectral extraction and collection of
metadata. The large number of extracted spectra (73,581) demanded automatic
methods for quality control and an automated classification algorithm was
trained on the visual inspection of several thousand spectra. The final sample
of quality controlled spectra includes 47,919 datasets (65% of the total number
of extracted spectra) for $32,149$ unique objects, with a median $i_{\rm
AB}$-band magnitude of 23.7, reaching 26.5 AB for the faintest objects. Each
released dataset contains science-ready 1D and 2D spectra, as well as
multi-band image cutouts of corresponding sources and a useful preview page
summarising the direct and slitless data, astrometric and photometric
parameters. In order to characterize the slitless spectra, emission-line flux
and equivalent width sensitivity of the ACS data were compared with public
ground-based spectra in the GOODS-South field. An example list of emission line
galaxies with two or more identified lines is also included, covering the
redshift range $0.2-4.6$.
