Use Jekyll incremental rebuilds for faster local editing

Problem and takeaway

On a medium or large Jekyll site, editing a single post can trigger a full regeneration of every page, post, and collection. That wait slows iterative editing. Jekyll’s incremental regeneration rebuilds only documents and pages whose source files changed since the last build, making it useful for local development. It is not safe for production or CI, and it does not detect changes to layouts, includes, _config.yml, or front-matter dependencies, so you must run a full build before deploying.

Prerequisites

• A Jekyll site in a local directory.
• Jekyll 3.3.0 or later; incremental regeneration was introduced in that version.
• Terminal access to the site root.
• Write permission to the site directory so Jekyll can create .jekyll-metadata.
• If the site uses Bundler, run commands through bundle exec.

Check the installed version

Run this in the site root:

jekyll -v

Expected result: Jekyll 3.3.0 or later. If the version is older, upgrade Jekyll before using --incremental.

Run an incremental build

From the site root, run:

jekyll build --incremental

Or, to start a local server with incremental regeneration and file watching:

bundle exec jekyll serve --incremental

The --incremental flag tells Jekyll to consult .jekyll-metadata in the site source and regenerate only documents and pages changed since the previous build. The first run after enabling the flag performs a full regeneration and writes the metadata file.

Edit one file and rebuild

1. Open one post or page, make a small text change, and save.
2. Run jekyll build --incremental again, or wait for the server to detect the change.
3. Confirm the build output lists only the edited document and pages that depend on it, such as the post index or feed.

If the output regenerates the entire site, incremental state was not reused. Common causes include a missing .jekyll-metadata file or an edit to a file Jekyll does not track incrementally.

When a full rebuild is required

Incremental regeneration does not reliably detect:

• Changes to _config.yml
• Changes to layout files in _layouts
• Changes to includes in _includes
• Front-matter changes that affect other documents, such as a category or tag used in a listing page

After any of these edits, stop the server if running, delete .jekyll-metadata, and run a full build:

rm .jekyll-metadata
jekyll build

This changes state by removing the incremental cache and forcing full regeneration. There is no separate rollback; rebuilding restores the site output.

Expected checks

• .jekyll-metadata exists in the site source after the first incremental build.
• A second build with no source changes reports few or no regenerated files.
• Editing one post rewrites that post and its dependent index or feed pages, not every collection.
• Deleting .jekyll-metadata causes the next build to regenerate the full site.

Limitations and risks

• Stale HTML can remain if a changed layout or include is not detected. Always run jekyll build without --incremental before deploying.
• GitHub Pages production builds do not use --incremental; the flag is for local development only.
• Very large source directories can still incur scanning overhead even when few files are regenerated.
• Browser live-reload depends on the serving setup and may not reflect every regenerated page.

Practical verification

Run jekyll build --incremental twice without changing sources. The second run should show reduced regeneration activity. Then edit one post, rebuild, and confirm only that post and related listing pages are rewritten. If you suspect stale output, delete .jekyll-metadata and run jekyll build to compare.