Show HN: I rewrote my notepad calculator as a local-first app with CRDT syncing

6 tonyonodi 1 6/30/2025, 8:10:27 AM numpad.io ↗

I launched NumPad v1 on here a few years ago, and back then it wasn't much more than a thin CodeMirror wrapper around the calculator engine I'd written.

Now I've rewritten it as a PWA that supports multiple documents, persists them to IndexedDB, and has a syncing service for paying customers. Syncing is handled by Automerge[1] under the hood, which should make it relatively easy to get document sharing working too.

[1] https://automerge.org/

Comments (1)

johncosta27 · 9h ago

This is very cool. I was able to so some a small budget to see what my expenses are monthly, it's quite nice. I can see myself using it anytime I need something more than paper, and less than a full spreadsheet. Very cool.

14.ai (YC W24) hiring founding engineers in SF to build a Zendesk alternative (14.ai)

Lago (Open-Source Usage Based Billing) is hiring for ten roles (ycombinator.com)

Spark AI (YC W24) is hiring a full-stack engineer in SF (founding team) (ycombinator.com)

Bitmovin (YC S15) Is Hiring a Junior Solutions Engineer in Denver (bitmovin.com)

SigNoz (YC W21, Open Source Datadog) Is Hiring DevRel Engineers (Remote)(US) (ycombinator.com)

AccessOwl (YC S22) is hiring an Elixir Engineer to connect 100s of SaaS (ycombinator.com)

FurtherAI (YC W24) Is Hiring for Software and AI Roles (ycombinator.com)

Yarn (YC W24) is hiring engineers in NYC (ycombinator.com)

Expand.ai (YC S24) is hiring a founding engineer

Optifye.ai (YC W25) is hiring a back end engineer

Kastle (S24) is hiring an engineer (ycombinator.com)

Weave (YC W25) is hiring a founding AI engineer (ycombinator.com)

Qfex (YC X25) – Back End Engineer for a 24/7 Stock Exchange (ycombinator.com)

Attimet (YC F24) – Quant Trading Research Lab – Is Hiring Founding Engineer (ycombinator.com)

Jiga (YC W21) Is Hiring Software Engs to Make Life of Mech Engs Easier (workatastartup.com)

Foundry (YC F24) Hiring Early Engineer to Build Web Agent Infrastructure (ycombinator.com)

Blaze (YC S24) Is Hiring (ycombinator.com)

Infracost (YC W21) is hiring software engineers (GMT+2 to GMT-6) (infracost.io)

Solidroad (YC W25) Is Hiring (solidroad.com)

Kyber (YC W23) Is Hiring a Technical Account Manager (ycombinator.com)

Roundtable (YC S23) Is Hiring a President / CRO (ycombinator.com)

Roame (YC S23) Is Hiring (ycombinator.com)

GauntletAI (YC S17): All expenses paid AI training and guaranteed $200k+ job (gauntletai.com)

SchemeFlow (YC S24) Is Hiring an Engineer (London) to Speed Up Construction (ycombinator.com)

Shaped (YC W22) Is Hiring (ycombinator.com)

Spice Data (YC S19) is hiring a software engineer – back end (ycombinator.com)

Onlook (YC W25) Is Hiring an engineer in SF

OneText (YC W23) Is Hiring a DevOps/DBA Lead Engineer (jobs.ashbyhq.com)

Gander (YC F24) Is Hiring Founding Engineers and Interns (ycombinator.com)

Ziina (YC W21) the Series A fintech is hiring product engineers (ziina.notion.site)

Show HN: I rewrote my notepad calculator as a local-first app with CRDT syncing

Comments (1)