A single-seed, module-based compact laser system is demonstrated on a transportable 87 Rb-based highprecision atomic gravimeter. All the required laser frequencies for the atom interferometry are provided by free-space acousto-optic modulators (AOM) and resonant electro-optic phase modulators (EOM). The optical phase-locked loop between two optical paths derived from the same laser provides an easy frequency manipulation between two laser frequencies separated by hyperfine frequency of 6.835 GHz using AOM and EOM respectively. The optical phase-locked loop also provides a convenient way for vibration compensation through the Raman lasers' phase offset. Furthermore, the modular design approach allows plug-and-play nature on each individual optic module and also increases the mechanical stability of the optical systems. We demonstrate high-precision gravity measurements with 17.8 µGal stability over 250 seconds averaging time and 2.5 µGal stability over 2 hours averaging time.