# What does Letter use?

Letter (letter.dev) shows public evidence of 10 tools, according to runsonwhat (last checked 2026-10-31).

- Industry: Engineering, Product and Design
- Size: 1–10 employees
- Based in: New York City, United States

## Edge & Hosting

| Tool | Category | Evidence | Since |
|---|---|---|---|
| [Vercel](https://www.runsonwhat.com/reverse/vercel) | Hosting & Cloud | DNS records |  |

## Application

| Tool | Category | Evidence | Since |
|---|---|---|---|
| [Next.js](https://www.runsonwhat.com/reverse/nextjs) | Frontend | Website code |  |

## Go-to-market

| Tool | Category | Evidence | Since |
|---|---|---|---|
| [Cal.com](https://www.runsonwhat.com/reverse/calcom) | Sales & CRM | Website code |  |
| [AthenaHQ](https://www.runsonwhat.com/reverse/athena) | Marketing | Website code |  |

## Company Ops

| Tool | Category | Evidence | Since |
|---|---|---|---|
| [Google Workspace](https://www.runsonwhat.com/reverse/google-workspace) | Workspace | Email records |  |
| [Let's Encrypt](https://www.runsonwhat.com/reverse/letsencrypt) | Security & Compliance | DNS records |  |
| [Sectigo](https://www.runsonwhat.com/reverse/sectigo) | Security & Compliance | DNS records |  |
| [Google Trust Services](https://www.runsonwhat.com/reverse/google-trust) | Security & Compliance | DNS records |  |

## FAQ

### What tools does Letter use?

As of November 2026, runsonwhat has found 10 tools at Letter (letter.dev) in public records. Edge & Hosting: Vercel. Application: Next.js. Go-to-market: Cal.com and AthenaHQ. Company Ops: Google Workspace, Let's Encrypt and Sectigo. Last checked October 31, 2026.

### What cloud does Letter run on?

Letter uses Vercel for hosting and cloud infrastructure, according to runsonwhat (November 2026). runsonwhat found Vercel through DNS records that point at Vercel. Vercel is used by 51,385 companies runsonwhat tracks.

### What sales tools does Letter use?

The sales tools runsonwhat has found at Letter are Cal.com (November 2026); no CRM shows up in Letter's public records. runsonwhat found Cal.com through Cal.com code on letter.dev. Cal.com is used by 932 companies runsonwhat tracks.

### What email provider does Letter use?

Letter uses Google Workspace for email and office software, according to runsonwhat (November 2026). runsonwhat found Google Workspace through email records that authorize Google Workspace. Google Workspace is used by 412,513 companies runsonwhat tracks.

### What marketing software does Letter use?

Letter uses AthenaHQ for marketing, according to runsonwhat (November 2026). runsonwhat found AthenaHQ through AthenaHQ code on letter.dev. AthenaHQ is used by 41 companies runsonwhat tracks.

### Does Letter use Next.js?

Yes. runsonwhat found Next.js at Letter through Next.js code on letter.dev. Next.js is a Frontend tool used by 69,170 companies runsonwhat tracks.

### Which companies have a tech stack similar to Letter's?

The companies with the stacks most like Letter's are Authologic, Coris, Dolby and Pago International, according to runsonwhat (November 2026). Each shares 2 to 9 tools with Letter, and rare tools count for more than common ones like Google Workspace, so the match reflects real stack choices.

### How does runsonwhat know what Letter uses?

runsonwhat reads public records only. Of the 10 tools at Letter, 5 were found through DNS records, 3 through code on letter.dev, 1 through email records and 1 through website configuration files. A tool is listed only when a direct record backs it up; DNS is rechecked weekly and letter.dev about monthly.


---

Source: runsonwhat, https://www.runsonwhat.com/company/letter.dev (updated November 2026). Counts are companies with direct public evidence of the tool (DNS records, certificates, website code, a real-browser crawl, subprocessor lists), so they are lower bounds. Methodology: https://www.runsonwhat.com/methodology.