usefulweb.appDependable little tools for people and AI agents. Fieldday
Theme: Auto

Theme

Sports club & training organiser

Fieldday

Fixtures, brackets, ratings and training plans for your club — in one workspace.

Launch Fieldday → Tutorials

Fieldday is a free workspace for club organisers, coaches and captains. Keep one roster and run Americano or Mexicano nights, tournament brackets, a league with title odds and what-if scenarios, Elo and Glicko-2 ratings fed by every scored match, away-trip fatigue and jet-lag plans, running and strength training plans and a shared calendar. Nine usefulweb tools do the maths; Fieldday connects them, keeps the history and turns it into a club report.

Free · runs in your browser · no sign-up · Version 1.0.0

Screenshots

Features

  • One roster for everything

    Players with skill, starting rating, group and status feed every workflow. Paste a list, import a CSV or receive a player table from another app — always with a review step.

  • Americano & Mexicano nights

    Fair doubles rounds with balanced sit-outs from the roster, scores typed straight into the court table, live standings and the next Mexicano round as soon as the scores are in.

  • Brackets with one-click results

    Single or double elimination or round robin, seeded as listed, by roster rating or by a reproducible draw. Pick winners in the match list and the bracket advances; export it as SVG or PNG.

  • League table & what-if scenarios

    Teams, fixtures and results in one table, a generated double round robin, title and relegation odds from a seeded simulation, and scenarios A/B/C compared side by side on the same random numbers.

  • Ratings fed by every match

    Scored mixer matches, bracket results and logged games become one Elo / Glicko-2 rating log, grouped by event, week or month, with win probabilities for any pairing.

  • Rating snapshots over time

    Save the ladder after every club night and compare: biggest movers, newcomers and a rating chart across snapshots.

  • Balanced teams in seconds

    Split the active players (or one group) into 2–8 teams balanced by skill with a seeded draw that anyone can reproduce.

  • Away-trip fatigue

    Travel distance, time-zone jumps, rest days and back-to-backs for every game of a road trip as a transparent 0–100 score, with the hardest game highlighted.

  • Jet-lag plans for long trips

    For trips across time zones: a day-by-day sleep, light and caffeine plan for the squad, suggested from the trip and downloadable as a calendar file.

  • Running training table

    Time trials per runner give race predictions, the goal-race time with even or negative splits and a progress line over the season — run for the whole group in one batch.

  • Strength block with plate loading

    Estimated one-rep maxes from test sets, progress since the first test and a percentage block whose weekly loads come with the plates to put on each side.

  • Club calendar & reminders

    Training slots repeated weekly, mixer nights, tournaments, fixtures and trip games in one agenda, exported as an .ics calendar with reminders.

  • Dashboard & club report

    Key numbers, plain-language findings, upcoming events and leaders on one page, plus a printable report (PDF via print) of every section.

  • Run everything in one go

    One click runs every section in dependency order — events first, then ratings — with progress, retry and clear messages when a tool rejects an input.

  • Local-first projects

    Autosave in this browser, recent projects, undo and redo, project files, share links, Google Drive (when connected) and hand-over of tables and brackets to other premium apps.

  • Same tools for scripts and AI agents

    Every calculation is a usefulweb tool with a JSON API and MCP; the documented project format lets an agent build a club file and open it in Fieldday.

Templates

Start from a ready-made project and change it to fit.

Built-in tools

Fieldday uses these tools. Each one also has its own page and works on its own, in the browser, through the JSON API and through MCP.

For AI agents

Fieldday runs on a deterministic engine. The same functions are available as tools with a JSON API and MCP, so scripts and AI agents get exactly the results the app shows.

  • Padel & Pickleball Scheduler – Fair Americano or Mexicano doubles rounds with balanced sit-outs, scores and standings.
    Tool page · POST https://fieldday.usefulweb.app/api/v1/tools/padel-pickleball-scheduler/calculate · MCP padel_pickleball_scheduler
  • Tournament Bracket Maker – Single or double elimination or round robin: seeded brackets, byes, results and downloads.
    Tool page · POST https://fieldday.usefulweb.app/api/v1/tools/tournament-bracket-maker/calculate · MCP tournament_bracket_maker
  • Elo/Glicko Rating Lab – Rate players from game results with Elo, Glicko-1 and Glicko-2; history chart and win odds.
    Tool page · POST https://fieldday.usefulweb.app/api/v1/tools/elo-glicko-rating-lab/calculate · MCP elo_glicko_rating_lab
  • Sports What-If Simulator – Simulate a match or a small league with a Poisson goal model — and replay “what if”.
    Tool page · POST https://fieldday.usefulweb.app/api/v1/tools/sports-what-if-simulator/calculate · MCP sports_what_if_simulator
  • Sports Travel-Fatigue Estimator – Travel distance, time-zone jumps, rest and back-to-backs per game as a fatigue score.
    Tool page · POST https://fieldday.usefulweb.app/api/v1/tools/sports-travel-fatigue-estimator/calculate · MCP sports_travel_fatigue_estimator
  • Running Pace & Splits – Pace, time or distance in km or miles, splits, race predictions, treadmill speed, laps.
    Tool page · POST https://fieldday.usefulweb.app/api/v1/tools/running-pace-calculator/calculate · MCP running_pace_calculator
  • One-Rep-Max & Plate Loader – 1RM from any set (7 formulas + average), % and RPE tables, and which plates to load.
    Tool page · POST https://fieldday.usefulweb.app/api/v1/tools/one-rep-max-calculator/calculate · MCP one_rep_max_calculator
  • Random Generator – Random numbers, dice, coins, list picks, shuffles, fair teams, dates, strings and UUIDs.
    Tool page · POST https://fieldday.usefulweb.app/api/v1/tools/random-generator/calculate · MCP random_generator
  • Jet Lag Planner – A day-by-day sleep, light and caffeine plan to beat jet lag, with calendar export.
    Tool page · POST https://fieldday.usefulweb.app/api/v1/tools/jet-lag-planner/calculate · MCP jet_lag_planner

Build a project through the API, then open it in the app with a link to https://fieldday.usefulweb.app/app#project=<base64url JSON>.

Import & export

Import

  • Fieldday project (.fieldday.json)
  • Player list (CSV/TSV or one name per line)
  • Player table from another premium app (App Bridge)
  • Project link (#project=…)

Export

  • Fieldday project (.fieldday.json)
  • CSV: roster, schedules, standings, fixtures, ratings, training tables
  • Bracket as SVG and PNG
  • iCalendar (.ics) with reminders
  • Jet-lag plan (.ics)
  • Printable club report (PDF via print)
  • Share link

Keyboard shortcuts

Keyboard shortcuts in Fieldday
KeysAction
Ctrl + EnterRun the tools of the current section
Ctrl + Shift + EnterRun every section
Ctrl + SSave project file
Ctrl + OOpen project file
Ctrl + Z / Ctrl + YUndo / redo
Ctrl + PPrint the club report
1 … 9Go to a section (dashboard … calendar)
NAdd an item to the current section
?Keyboard shortcuts

Frequently asked questions

Is Fieldday free? Do I need an account?

Yes, it is free and needs no account. Projects are saved in your browser (IndexedDB) and as files you download; with Google Drive connected you can also save them there.

Where are the calculations done?

The nine built-in tools run on usefulweb’s server through the same JSON API that scripts use; Fieldday sends only the inputs of the section you run (names, scores, dates, times) and keeps the results in your project. Editing works offline; running a tool needs a connection.

How do mixer matches count in the ratings?

A scored doubles match counts as one game between each player and each player on the other side of the net (four games per match): a win for both winners against both losers, a draw for equal points. You can switch this off per session or tournament.

Why are rating periods important?

Glicko rates all games of a period together. Fieldday groups the log by event (each club night or tournament), ISO week or month; Elo is updated game by game either way. One run rates the latest 200 games.

How reliable are the league odds?

They come from a Poisson goal model (from goal averages or Elo ratings) simulated thousands of times with a fixed seed. It ignores injuries, form and motivation, so treat it as an informed what-if, not a forecast for betting.

Is the fatigue score a medical measurement?

No. It is a transparent heuristic with documented weights for distance, time-zone shift, rest and schedule density, useful to compare trips. The jet-lag plan follows CDC rules of thumb and is not individual medical advice.

Can I share a tournament with players?

Copy a share link (it contains the whole project in the link, nothing is stored on a server), print the report, export the bracket as SVG or PNG, or export the calendar as .ics.

Can an AI agent create a Fieldday project?

Yes. The project format is the JSON Schema at /static/apps/fieldday/fieldday.schema.json (also served at /project.schema.json), and every tool is available over the JSON API and MCP on fieldday.usefulweb.site. An agent can build a project and open it with /app#project=<base64url JSON>.

Limitations

What Fieldday does not do (yet):

  • Fieldday is an organiser, not a booking system: no online sign-ups, payments, messaging or member logins.
  • Tools run on the usefulweb server: without a connection you can edit and view saved results but not run new calculations.
  • Mixer nights are doubles only (4 players per court); singles ladders go through tournaments and the game log.
  • One rating run uses the latest 200 games and at most 100 starting ratings; older games stay in the log.
  • The league simulator handles up to 16 teams and 240 fixtures with a Poisson goal model (football-style scores).
  • Travel fatigue knows 118 major sports cities; other venues need latitude,longitude and a time zone.
  • Training plans cover running paces and barbell percentages; there is no heart-rate, GPS or wearable import.
  • Calendar files are exported, not synced: re-export after changes.

Tutorials

Learn Fieldday step by step.

  1. Your first club night in 5 minutesAdd your players, draw a padel or pickleball Americano, enter the scores court by court and read the live standings. Nothing to install.Beginner 5 min
  2. Mexicano rounds and tournament bracketsRun a Mexicano round by round, then seed a single- or double-elimination bracket from your ratings, click winners and export the bracket as SVG or PNG.Beginner 8 min
  3. League table, title odds and what-if scenariosGenerate a round robin, enter the results so far, simulate the rest of the season and compare scenarios such as “we win the derby” side by side.Intermediate 10 min
  4. Ratings from every matchTurn mixer scores, bracket results and logged games into Elo and Glicko-2 ratings, save snapshots and see who moved since last month.Intermediate 8 min
  5. Away trips, fatigue and jet lagPlan a road trip game by game, see distance, time-zone shifts, back-to-backs and a fatigue score per game, and add a jet-lag plan with a calendar file.Intermediate 7 min
  6. Training plans for runners and liftersTrack time trials and test sets, get race predictions, goal paces and splits, estimated one-rep maxes and a loaded percentage block with plates per side.Intermediate 10 min
  7. Calendar, club report and sharingBuild a weekly training schedule, export everything to your calendar with reminders, print a club report, share a project by link or send tables to other apps.Beginner 6 min

Ready to try it?

Launch Fieldday →

Other premium apps