Draw a round robin for your 42 teams, print a score sheet for every game, and type the final marks as games finish: the standings and seeding order keep themselves.
Texas 42 tournament
Names and scores are saved on this device only, so keep scoring on one phone or computer. The share link carries the draw (format, size, rounds), never names or scores.
Print
Standings
Scores by round
Type each side's final marks when a table finishes.
How a 42 tournament runs
A typical 42 tournament plays a round robin first and uses it to seed the bracket. Under the Austin 42 tournament rules the morning round robin is drawn at random, games are to 7 marks, and teams are seeded by win record, then total marks won, then the fewest marks scored against them; if still level, by one hand or each team drawing a domino. The standings here use that order, so the top of the table is your seed list. Number the teams by drawing lots before you start, since Austin draws its round robin at random.
Austin awards every mark scored. The sample tournament rules at texas42.net instead add up each team's marks over its round-robin games with no more than 7 marks a game; tick "Count at most 7 marks a game" for that rule.
Austin's round-robin games also have a 25-minute limit: when time is called the hand in progress is finished, and if the game is tied one more hand decides it. That is why the planner accepts a winner below 7 marks but never a tied game.
The printouts: a seating chart for the host, a score sheet for every table and round with the teams filled in and lines for the scorekeeper and the other team to sign, score cards, and a results sheet (a blank one to fill in by hand before any scores are typed).
Questions organizers ask
How many marks is a game of 42?
Seven. A team scores a mark for making its bid, or for setting the other team; a bid of 84 is worth two marks.
How are 42 tournament teams seeded?
Under the Austin 42 tournament rules: win record first, then total marks earned, then the fewest marks scored against, then one hand or a domino draw.
What does a forfeit count?
Austin 42 scores a forfeit 7 to 0. Type 7 for the team that was present and 0 for the absent team.
What if we have an odd number of teams?
One team has a bye each round. Only a full round robin (as many rounds as teams) gives every team exactly one bye, so that is the suggested length up to 11 teams. With fewer rounds some teams play one game more; the planner names them and ranks by share of games won and marks per game instead of totals.
Sources: Austin 42 tournament rules (austin42.org); 42 tournament sample rules (texas42.net); City of Marshall, Texas 42 tournament rules. Not affiliated with any of them.