Without a doubt you are going to need a piece of software to take advantage of arbitrage opportunities as it is impossible to take advantage of them otherwise, however do you have the capital to pull this off? Arbitrage trading can be profitable but since the profit of each trade is low and you need to have several accounts in different exchanges then the amount of money needed to become profitable is incredibly high, so unless you can fulfill this requirement then you should forget about it for the time being.
I remember the time when it was possible to do without a bot for arbitrage trading, but now everything has changed and it is impossible for you to do without bots to get a profit. With such volatility in the cryptocurrency market, you can make a profit without wasting time on arbitrage trading.
Personally I never tried to manually try to look for arbitrage opportunities, however it does not surprise me at all to find out that this was possible to do so at some point in time in this market, but what happens is that this market is slowly moving from a bunch of people with libertarian ideals to institutional investors, and once that transition happened then it became quite more difficult to profit from the markets as they bring not only a lot of capital but their tools as well, and this includes arbitrage bots as well.