---
title: "Let's Encrypt API changes, deprecations and deadlines | Harbyn"
description: "Let's Encrypt: 1 upcoming deadline and 2 recorded changes as of 2026-10-25, each with its source."
canonical: "https://harbyn.com/vendors/letsencrypt"
last-updated: 2026-10-08
---

# Let's Encrypt: API changes and deadlines

Markdown version of <https://harbyn.com/vendors/letsencrypt>.

Developer tools. 1 upcoming deadline, 2 recorded changes. Every entry cites the Let's Encrypt page we read it from.

## What we read

The Let's Encrypt pages and feeds our ingestion visits, politely and on a schedule.

- **Changelog**: <https://letsencrypt.org/feed.xml>
- **Changelog**: <https://api.github.com/advisories?affects=acme-client&per_page=20&sort=published&direction=desc>

## What the scanner looks for

How `harbyn scan` recognises Let's Encrypt in a repository, on your machine. Nothing leaves it.

- **Packages**: `npm acme-client`
- **API hosts**: `acme-v02.api.letsencrypt.org`

## Upcoming deadlines

| Deadline | Change | Use instead | Details | Source |
| --- | --- | --- | --- | --- |
| Feb 10, 2027 | Default certificate lifetime changes to 64 days | - | <https://harbyn.com/changes/letsencrypt/2026-10-07-64-day-certificate-lifetimes-coming-feb-2027.md> | <https://letsencrypt.org/feed.xml> |

## Change history

Newest first, by the date Let's Encrypt announced it. This is the archive: past changes are not warnings, and changes we recorded after they took effect are marked as such.

### October 2026

- Oct 7, 2026, Behavior change: [ACME authorization reuse period cut from 30 to 10 days](https://harbyn.com/changes/letsencrypt/2026-10-07-64-day-certificate-lifetimes-coming-feb-2027-2.md)