Help them feel close, every month.
A monthly letter-writing kit for both your grandparent and grandchild. Pre-stamped. Pre-addressed. With fun sparks. Just write and mail.
$0 today, then $19.99/month for both kits. Cancel anytime.
Try the first month free. If it's not magic, cancel before you're charged.
Why families love it
More than mail.
A monthly moment with someone you love.
They couldn't wait to read what each other had said.
"My daughter and mom were so impressed by these cards! They immediately filled them out and couldn't wait to read what each other had said."
— — Latoya
How it works
Step 1
Pick your pair
Pick the two people in your family who want to stay close — grandparent & grandchild, partner & partner, parent & kid. Add their addresses.
Step 2
Kits arrive each month
Each person gets a spark card and a pre-stamped, pre-addressed envelope to the other. You'll never run out of something to write about.
Step 3
Write, seal, mail
Fill out the card, slip it in the envelope, drop it in any mailbox. Watch your fridge — and theirs — fill up with letters.
Made for every family
Starting at $0 today, then $19.99/month
All plans include:
- Kits for both people every month
- Pre-stamped USPS Forever envelopes
- Pre-addressed to each other
- Fresh sparks — never repeat
- Age-appropriate designs (kids & grandparents)
- Free shipping
Give Heartstring
The gift that arrives in two mailboxes — every month.
Pay once, and kits arrive for both people every month. Pre-stamped, pre-addressed, with fresh prompts. Perfect for birthdays, holidays, or just because.
3-Month Gift
Three months of letters — save $5
- ✓ 3 months of kits for both people
- ✓ Pre-stamped, pre-addressed envelopes
- ✓ Fresh sparks every month
6-Month Gift
Half a year of mailbox moments — save $20+
- ✓ 6 months of kits for both people
- ✓ Pre-stamped, pre-addressed envelopes
- ✓ Fresh sparks every month
Want to try it for yourself first? Start a free month →
Questions
What comes in each kit?
A spark card designed for their age, a pre-stamped USPS Forever envelope addressed to the other person, and simple instructions.
Who is this for?
Any two people who want to stay in touch. Most popular: grandparent + grandchild (ages 5–14). Also great for long-distance couples and college kids & parents.
How do gift subscriptions work?
Enter both addresses, pick a plan, add a gift message. Kits start arriving the next month.
What if my grandchild is too young to write?
For little ones who can't write yet, we have sparks for parents to fill in about their child's journey through life — milestones, funny moments, favorites — plus mementos like hand tracings. Grandparents love these.
Do sparks repeat?
Never. Fresh every month.
Why not just buy stamps myself?
You could. Most people intend to. But the small barriers add up and it never happens. Heartstring removes every barrier except the writing.
Can I change addresses?
Yes, anytime from your dashboard. Changes apply to the next kit. US addresses only for now.
Try the first month free
$0 today, then $19.99/month for both people. Cancel anytime — no charge for 30 days.