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tashian merged 3 commits into from
Nov 6, 2025
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Add acme-tiny to ACME tutorial #453

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Add tiny-acme
tashian Nov 6, 2025
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Update tutorials/acme-protocol-acme-clients.mdx
tashian Nov 6, 2025
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Update tutorials/acme-protocol-acme-clients.mdx
tashian Nov 6, 2025
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37 changes: 36 additions & 1 deletion tutorials/acme-protocol-acme-clients.mdx
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Original file line number Diff line number Diff line change
@@ -1,5 +1,5 @@
---
updated_at: September 18, 2025
updated_at: November 06, 2025
title: Configure popular ACME clients to use a private CA with the ACME protocol
html_title: Configure ACME Clients with step-ca Tutorial
description: Configure popular ACME clients with step-ca. Support for Certbot, acme.sh, and other ACME implementations for automated certificate management.
Expand Down Expand Up @@ -97,6 +97,7 @@ Choose a renewal period that is two-thirds of the entire certificate's lifetime,
* [Certbot](#certbot)
* [acme.sh](#acmesh)
* [lego](#lego)
* [acme-tiny](#acme-tiny)
* [win-acme](#win-acme)
* [Caddy v2](#caddy-v2)
* [NGINX](#nginx)
Expand Down Expand Up @@ -233,6 +234,40 @@ You can automate renewal with a simple `cron` entry:
*/15 * * * * root LEGO_CA_CERTIFICATES="$(step path)/certs/root_ca.crt" lego [email protected] -d foo.internal --http renew
```

### acme-tiny

[acme-tiny][] is a minimalist ACME client that provides just what you need for automated certificate issuance—nothing more.
It's written in Python and is designed to be simple, auditable, and easy to understand.

[acme-tiny]: https://github.com/diafygi/acme-tiny

To get a certificate from `step-ca` using `acme-tiny` you need to:

1. Point `acme-tiny` at your ACME directory URL using the `--directory-url` flag
2. Tell `acme-tiny` to trust your root certificate using the `REQUESTS_CA_BUNDLE` environment variable

For example:

```shell
REQUESTS_CA_BUNDLE=$(step path)/certs/root_ca.crt \
python acme_tiny.py \
--account-key account.key \
--csr domain.csr \
--acme-dir /var/www/challenges/ \
--directory-url https://ca.internal/acme/acme/directory \
> signed_chain.crt
```

`acme-tiny` uses the `http-01` challenge type, where it writes challenge files to a directory that your web server serves. You'll need to configure your web server to serve files from the directory specified by `--acme-dir`.

You can automate renewal with a simple `cron` entry:

```shell
0 0 * * * REQUESTS_CA_BUNDLE=$(step path)/certs/root_ca.crt python /path/to/acme_tiny.py --account-key /path/to/account.key --csr /path/to/domain.csr --acme-dir /var/www/challenges/ --directory-url https://ca.internal/acme/acme/directory > /path/to/signed_chain.crt 2>> /var/log/acme_tiny.log
```

Like with `certbot`, you'll want to adjust the renewal frequency based on your certificate lifetime. For `step-ca`'s default 24-hour certificate lifetimes, you may want to run renewals more frequently.

### win-acme

[win-acme][] (`wacs.exe`) is a popular ACME client for Windows.
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