How does the diff work?

You mark one version as Diff (left) and another as Diff (right); the tool then computes a line-based longest-common-subsequence diff between the two texts. Equal lines render neutral, added lines green with a + prefix, removed lines red with a − prefix, and badges summarise "+N added / −N removed". Picking the same version twice shows an amber warning to choose two different versions.

Does restoring a version delete anything?

No. Restore copies the selected snapshot's name and text back into the editor fields, leaving the entire history untouched. The intent is to recover an older wording so you can keep editing or save it as a new snapshot. The current editor content is simply replaced — unsaved edits are lost, so save a version first if you want to keep them.

Can I import versions exported from another browser?

Yes. Export downloads prompt-versions.json containing the whole library; Import accepts either that wrapped shape or a bare array of versions, validating name, text, and a numeric createdAt on each entry. Merging skips versions whose id already exists, so importing the same file twice is safe. New ids are generated for entries missing one.

How is this different from the Prompt Library?

The Library stores many different reusable prompts; the Version Manager stores the history of one prompt (or a few) over time. The Library optimises for browsing and copying a catalogue, while the Version Manager optimises for snapshots, messages, restore, and diffs. They complement each other: keep finished prompts in the Library and iterate draft wording in the Version Manager.

What does Clear all actually delete?

Every saved version, after a confirmation dialog that states the count and warns the action cannot be undone. The editor fields are left as they are, but the timeline, stats, and any selected diff sides reset to empty. If the history matters, run Export first — the JSON file is the only recovery path once localStorage has been cleared.

Misc

Prompt Version Manager

Track prompt versions with diff, restore, and export.

promptversionhistorydiffrestore

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About the Prompt Version Manager

The Prompt Version Manager brings lightweight version control to prompt engineering. Give a prompt a name, paste its text, add an optional save message, and click Save version — the tool snapshots the exact text with a timestamp into a timeline grouped by prompt name. From there you can restore any historical version back into the editor, mark two versions as left and right to run a line-by-line diff with additions in green and removals in red, or delete individual snapshots. Stats cards report how many versions you have saved, how many distinct prompts they cover, and when your latest save happened, with relative timestamps such as "5m ago". The whole history exports to a single JSON file and imports back on any device, merging by version ID so duplicates are skipped. Data lives in localStorage under the fl-prompt-versions key — nothing is uploaded. This prompt history tracker is ideal for A/B testing prompt wording: save a version before each experiment so you can always explain, compare, or roll back a change instead of trying to remember what worked last week.

Hand-written guide

Examples

Input

Prompt name: Code review assistant
Text:
You are a senior code reviewer. Review the following {{language}} code for {{concerns}}.
Respond in plain text.
Flag security issues explicitly.
Message: initial version

Output

Stats update to Saved versions 1 · Distinct prompts 1 · Latest save "just now". The timeline shows the snapshot grouped under "Code review assistant" with its timestamp, the save message, a 280-character text preview, and a "latest" badge.

Note: Both a prompt name and non-empty text are required — the form refuses to save otherwise.

Input

Edit the text to swap the second line for "Respond in JSON. Output only the JSON object.", set the save message to "added JSON output spec", and click Save version.

Output

Code review assistant — 2 versions
· [timestamp] · added JSON output spec · latest
· [timestamp] · initial version
Stats: Saved versions 2 · Distinct prompts 1 · Latest save just now

Note: Both snapshots stack under the same prompt name in newest-first order, with the newest marked latest.

Input

Click Diff (left) on the "initial version" snapshot and Diff (right) on the newest one.

Output

+1 added  −1 removed
  You are a senior code reviewer. Review the following {{language}} code for {{concerns}}.
− Respond in plain text.
+ Respond in JSON. Output only the JSON object.
  Flag security issues explicitly.

Note: Green lines are additions, red lines removals; the diff card also shows both version headers with name, timestamp, and message.

How to use

1
Enter a Prompt name and the prompt text, plus an optional Save message describing what changed, then click Save version.
2
Watch the stats update — Saved versions, Distinct prompts, and Latest save — and the snapshot appear on the timeline under its prompt name.
3
Edit the text further and save again; repeat snapshots stack under the same name with the newest marked latest.
4
Pick two snapshots via their Diff (left) and Diff (right) buttons to open the line-by-line comparison with added and removed counts.
5
Use Restore to copy any snapshot back into the editor, or Export / Import to move the whole history between devices as JSON.

Common use cases

A/B test prompt wording — snapshot before each change so any experiment can be compared or rolled back.
Track how a production prompt evolved — a grouped timeline with messages documents every tweak and its rationale.
Recover an earlier draft — restore a snapshot whose wording outperformed later "improvements".
Review prompt changes with a teammate — the side-by-side diff makes it trivial to see what changed line by line.
Port prompts between machines — export the whole history as JSON and import it with duplicate-safe merging.
Prepare a prompt release — diff the current candidate against the last shipped version before going live.

Best practices

Write a save message every time: the timeline shows the message next to each snapshot, and "tightened tone, added JSON output spec" beats "No save message" when you diff a month later.
Save before every A/B change, not after: a snapshot of the pre-change text is what makes the diff meaningful when you compare old and new wording.
Diff across the same prompt name: the timeline groups versions by prompt name, so keep one consistent name per prompt and let messages carry the change notes.
Restore is non-destructive: it copies the old name and text into the editor and keeps the history intact, so restore freely and save again if you want a new snapshot.
Export the JSON before clearing localStorage or switching browsers — the fl-prompt-versions key lives only in this browser, and the export is the only portable copy.
Delete experiments that lost: trimming failed variants keeps the timeline readable, since diffing works the same regardless of how many snapshots remain.

Tips

The Latest save stat is relative ("just now", "5m ago") — a quick way to confirm a save actually landed.
Timestamps are your index: the message tells you why a version exists, and the timestamp tells you when.
Diff (left) and Diff (right) can be picked in any order, and clicking a selected side again deselects it.
Restore copies name and text into the editor without touching history — use it to resurrect wording you want to edit further.

Frequently asked questions

Four fields: a unique version id, the prompt name, the full text, the optional save message, and a createdAt timestamp. The name groups snapshots on the timeline, the message explains the change, and the timestamp powers the relative "5m ago" display plus the Latest save stat. Nothing else is captured — no diffs are precomputed; comparisons run on demand.

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