---
title: "Mastodon Instance Tuning"
domain: selfhosting
category: services
tags: [mastodon, fediverse, self-hosting, majortoot, docker]
status: published
created: 2026-04-02
updated: 2026-04-02
---

# Mastodon Instance Tuning

Running your own Mastodon instance means you control the rules — including limits the upstream project imposes by default. These are the tweaks applied to **majortoot** (MajorsHouse's Mastodon instance).

## Increase Character Limit

Mastodon's default 500-character post limit is low for longer-form thoughts. You can raise it, but it requires modifying the source — there's no config toggle.

The process depends on your deployment method (Docker vs bare metal) and Mastodon version. The community-maintained guide covers the approaches:

- [How to increase the max number of characters of a post](https://qa.mastoadmin.social/questions/10010000000000011/how-do-i-increase-the-max-number-of-characters-of-a-post)

**Key points:**
- The limit is enforced in both the backend (Ruby) and frontend (React). Both must be changed or the UI will reject posts the API would accept.
- After changing, you need to rebuild assets and restart services.
- Other instances will still display the full post — the character limit is per-instance, not a federation constraint.
- Some Mastodon forks (Glitch, Hometown) expose this as a config option without source patches.

## Media Cache Management

Federated content (avatars, headers, media from remote posts) gets cached locally. On a small instance this grows slowly, but over months it adds up — especially if you follow active accounts on large instances.

Reference: [Fedicache — Understanding Mastodon's media cache](https://notes.neatnik.net/2024/08/fedicache)

**Clean up cached remote media:**

```bash
# Preview what would be removed (older than 7 days)
tootctl media remove --days 7 --dry-run

# Actually remove it
tootctl media remove --days 7

# For Docker deployments
docker exec mastodon-web tootctl media remove --days 7
```

**Automate with cron or systemd timer:**

```bash
# Weekly cache cleanup — crontab
0 3 * * 0 docker exec mastodon-web tootctl media remove --days 7
```

**What gets removed:** Only cached copies of remote media. Local uploads (your posts, your users' posts) are never touched. Remote media will be re-fetched on demand if someone views the post again.

**Storage impact:** On a single-user instance, remote media cache can still reach several GB over a few months of active federation. Regular cleanup keeps disk usage predictable.

## Gotchas & Notes

- **Character limit changes break on upgrades.** Any source patch gets overwritten when you pull a new Mastodon release. Track your changes and reapply after updates.
- **`tootctl` is your admin CLI.** It handles media cleanup, user management, federation diagnostics, and more. Run `tootctl --help` for the full list.
- **Monitor disk usage.** Even with cache cleanup, the PostgreSQL database and local media uploads grow over time. Keep an eye on it.

## See Also

- [self-hosting-starter-guide](../docker/self-hosting-starter-guide.md)
- [docker-healthchecks](../docker/docker-healthchecks.md)