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TinyCron

Core Problem

Developers and DevOps engineers waste time guessing whether a cron expression will fire correctly. Most cron tools are either CLI-only (crontab -g style) or online visualizers that don't provide testing with real datetime inputs. No history, no export, no team sharing.

Key Features (3-5 maximum)

  1. Cron Parser & Visualizer — paste cron expression → show human-readable schedule (e.g., "Every Monday at 9:00 AM UTC") with visual next-occurrence timeline.
  2. Next 10 Runs Calculator — given a reference datetime, compute the next 10 execution times with timezone support.
  3. Cron Generator — guided UI to build cron expressions (select minute/hour/day/month/weekday) → auto-generate string.
  4. History Library — localStorage saves previously tested cron expressions for quick re-testing.
  5. Copy & Export — one-click copy cron string; export history as CSV for team documentation.

Tech Stack Suggestion

  • Next.js 15 (App Router) + React 19 + TypeScript
  • Lightweight cron parser library (e.g., cron-parser or cronstrue) via npm
  • Shadcn/ui components (inputs, select dropdowns, copy buttons, timeline cards)
  • Client-side only: localStorage for history (no DB/auth)
  • Zero external APIs: all computation in-browser

Why Buildable in 2-3 Days

  • Focused scope: single input field + parsed output + timeline. No auth, no backend, no webhooks.
  • Off-the-shelf parsing: cron-parser handles the heavy lifting; cronstrue gives human-readable summaries.
  • Simple UI: form inputs + timeline cards ~4-6 hours. Generator UI is 2-3 hours.
  • No complex state: no real-time updates, no drag-drop, no database migrations.
  • Clear deliverables: 5 features, each ~3-4 hours. Total: ~14-16 hours for polished MVP.
  • Unit test friendly: cron logic is deterministic; easy to test edge cases (leap years, timezones).

Target Users

  • Developers deploying cron jobs (Vercel, Railway, AWS Lambda, GitHub Actions).
  • DevOps/SREs validating schedules before production rollout.

Feasibility Gut-Check (2-3 day budget)

  • Cron parsing & visualization: 4h (library integration, human-readable output).
  • Next-10-runs calculator: 3h (datetime math, timezone handling).
  • Generator UI: 3h (select dropdowns → string builder).
  • History (localStorage): 2h (CRUD, search/filter).
  • Copy/export: 1h (CSV generation, clipboard copy).
  • Tests + docs: 3-4h (unit tests for datetime math, E2E happy path).
  • Total: ~16-17 hours — fits within 2-3 day build window.

🧠 Brainstorm Review (2026-07-19)

Score: 12/15 — Feasibility 5 · Market Fit 2 · Complexity 5 → ⏸️ Deferred (Market-Fit gate, MF≤2) Trivially buildable (off-the-shelf cron-parser / cronstrue, pure client-side, ~16h) but out-competed by a free dominant incumbent: crontab.guru already does human-readable parsing + next-runs, free, excellent, and is the de-facto standard. The "history + CSV + generator + timezone" additions are minor features, not a wedge — a user who needs to recall a cron expression just bookmarks crontab.guru. Same buildable-but-no-demand-edge trap as PickOne (014) / CommitLift (029). Rescue: a narrow wedge — e.g. a cron linter / dry-run against a real clock with DST/edge-case warnings, or natural-language → cron for non-engineers, or drop.