The family apps: paying monthly for the teaching layer
Greenlight is the category’s heavyweight: debit card with parental controls, chores and allowance automation, and custodial investing where kids research and propose trades parents approve — the best pure teaching mechanism in the market. The honest cost: plans run roughly $6–$15/month, which is real drag on small balances; the value case is the financial education, not the investing economics. Best for: families who’ll actively use the teaching tools with kids roughly 8–17.
Acorns Early (the custodial side of Acorns) leans automation: round-ups and recurring deposits into diversified portfolios — the “set it and let it grow” pick inside a subscription many families already pay for. UNest pitches simplicity for gift-heavy families; EarlyBird makes relatives’ gifting genuinely delightful (video messages attached to investments). Both charge monthly or asset-based fees that matter at small balances — fine as gifting rails, weak as pure growth engines.
The traditional brokerages: free, powerful, and silent
Fidelity and Charles Schwab both offer custodial (UTMA/UGMA) brokerage accounts with zero monthly fees, zero minimums, and full market access — every stock, ETF, and index fund, with fractional shares. On pure investing economics nothing beats them: a custodial index-fund position compounding fee-free for fifteen years is the quiet optimum.
What they don’t do is teach: no kid-facing app, no chore systems, no training wheels — a parent-driven experience. Fidelity’s separate Youth Account (for teens 13–17, teen-owned rather than custodial) adds a genuinely good free teen debit-and-invest experience worth knowing about. Best for: parents comfortable driving, balances meant to grow untouched, and anyone allergic to subscription drag.
The verdict grid: who should pick what
Want a kid actively learning money? Greenlight — the monthly fee buys the best teaching machine; cancel it when the lessons are learned and the balance can migrate. Want automated growth with zero effort? Acorns Early if you’re already in Acorns; otherwise a free brokerage with a recurring transfer does the same for nothing. Want maximum growth economics? Fidelity or Schwab custodial, index funds, done. Want relatives funding the future? EarlyBird or UNest make gifting frictionless.
Two honest warnings that apply everywhere: custodial money legally becomes the child’s at majority — plan for an 18-year-old owning it — and custodial assets carry that settled-but-unfavorable ~20% FAFSA assessment (the financial-aid deep-dive covers the landscape). For most families the complete stack reads: Trump Account free money → 529 if college is the goal → custodial for flexibility and teaching → the app layer only while it’s earning its fee.