As transistor scaling is slowing down , other opportunities for ensuring continuous performance increase have to be explored. Field programmable gate arrays (FPGAs) are in the spotlight these days: not only due to their malleability and energy efficiency, but also because FPGAs have recently been integrated into the cloud . The latter makes them available to everyone in need of the immense computing power and data throughput they can offer. However, one important issue needs to be resolved first - the time to compile an industrial-scale design for an FPGA must be drastically reduced. Researchers have been looking for ways to accelerate FPGA routing through parallelism, since routing is one of the most time-consuming compilation steps. However, the ideal solution has not been found yet. This paper provides a survey of parallel FPGA routers, with the aim to identify their strengths and weaknesses, thus suggesting directions to take in further efforts for acceleration.