Versioned by default
Every edit is saved as a new version-nothing is overwritten. Keep a complete, reviewable history of how each prompt evolved.
Prompt Management
Version every prompt, ship with confidence
Manage your prompts in one library where every change is a new version. Edit with a visual diff, compare versions side by side, roll back instantly, and optimize with GEPA-so you can improve prompts without ever losing a known-good one.
No credit card required · Free to start
Prompt studio
support-triage
Updated 2h ago by [email protected]
System
You are a support specialist for {{company}}. Reply in a {{tone}} tone and resolve the issue in the fewest steps.
User
Customer message: {{ticket}}
Variablescompanytoneticket
gpt-5.5 · temp 0.3Save new version
Why FastRouter prompt management
Treat prompts like the production assets they are
Prompts drive your product's behavior. FastRouter gives them version control, a shared home, and built-in optimization-so changing a prompt is fast, safe, and reviewable.
One library for every prompt
Author messages, template variables, and model settings in a single place your whole team works from, scoped by project permissions.
Optimization built in
Run GEPA prompt optimization on any prompt and save the improved result straight back as a new version-no copy-pasting between tools.
How it works
From first draft to optimized version
Author a prompt, save versions as you iterate, compare and roll back when you need to, and optimize with GEPA-all without leaving the prompt library.
Step 1
Author
Write messages with reusable template variables and a model.
Step 2
Version
Every save is a new version with a visual diff of what changed.
Step 3
Compare & roll back
Diff any two versions side by side and restore in one click.
Step 4
Optimize
Run GEPA optimization and save the winner as a new version.
Prompts
3NameVersionModelStatusUpdated
- support-triagev4gpt-5.5Productionv4 live
- sql-generatorv9claude-opus-4.8Stagingv9 live
- doc-summarizerv2gemini-3-proDraftv2 live
Shared across your team · governed by project permissions
Versioning
Every change is a new version you can trust
Editing a prompt never overwrites the last one. FastRouter captures each save as a version with a clear diff of exactly what changed-so you can iterate quickly without losing a known-good prompt.
Visual diff on save
Review added and removed lines before you commit a new version, so every change is intentional.
Complete history
See every version with who changed it and when, all the way back to the first draft.
Roll back anytime
If a change underperforms, restore an earlier version in one click and keep moving.
Version history
v3 → v4 diff
− Reply and resolve the issue.
+ Reply in a {{tone}} tone and resolve in the fewest steps.
- v4Current
Tighten tone, add escalation rule
maya · 2h ago
- v3Restore
Add {{ticket}} variable
raj · 1d ago
- v2Restore
Shorten system prompt
maya · 3d ago
- v1Restore
Initial prompt
raj · 1w ago
Compare versions
See exactly what changed, side by side
Pick any two versions and compare them in a side-by-side diff. Added lines are highlighted in green and removed lines in red, so the impact of every edit is obvious at a glance.
Side-by-side diff
Line up two versions and read the changes in context instead of guessing from memory.
Compare any two versions
Diff the current prompt against the last release-or any two points in its history.
Decide with confidence
Confirm what a change touched before you promote it, so nothing ships by surprise.
Compare versions
v2Older
·You are a support specialist.
−Answer the question.
−Be brief.
·Escalate billing issues.
v4Current
·You are a support specialist.
+Reply in a {{tone}} tone.
+Resolve in the fewest steps.
·Escalate billing issues.
removed added2 changes
Optimize
Improve prompts, then version the winner
Prompt management is wired directly into GEPA prompt optimization. Launch an optimization run from a prompt, and the improved prompt comes back as a new version-ready to diff, compare, and promote.
GEPA optimization
Reflection-driven mutations and LLM-judge scoring evolve your prompt toward higher quality.
Measurable lift
Each run reports how much the optimized prompt improved over the version you started from.
Saved as a version
The optimized prompt lands back in version history, so adopting it is a reviewed, reversible step.
Optimize with GEPA
v4 baseline0.71
Optimized0.89
+25%score
ReflectionMutationLLM-judge scoring
Saved as v5 · Optimized
Review the diff, then promote it when you're ready.
Managed prompts vs prompts in code
Why move prompts out of your codebase
Hardcoded prompts have no history, no diff, and no easy way to roll back. A versioned prompt library gives every change structure, review, and a path to improvement.
| Capability | Prompts in your codebaseScattered in code | FastRouter prompt managementOne versioned library |
|---|---|---|
| Iterate safely | ||
| Full version history | Not included | Included |
| Visual diff on every change | Not included | Included |
| Compare any two versions | Not included | Included |
| Roll back to an earlier version | Not included | Included |
| Improve & collaborate | ||
| One-click GEPA optimization | Not included | Included |
| Shared library across the team | Not included | Included |
| See who changed what and when | Not included | Included |
| Reusable template variables | IncludedManual | Included |
“Manual” = achievable with custom code and discipline, but not provided or tracked for you.
Use cases
Built for teams shipping prompt changes
From solo builders to large AI teams, prompt management turns prompt edits into a fast, reversible, collaborative workflow.
Iterate without fear
Tune a production prompt knowing every previous version is saved and one click away if a change misfires.
Keep teams in sync
Give engineers, PMs, and prompt authors one shared library instead of prompts copy-pasted across repos and docs.
Template once, reuse everywhere
Define prompts with variables like company, tone, and ticket so the same prompt adapts to every request.
Ship measured improvements
Optimize a prompt with GEPA, compare the lift against the current version, and promote only what wins.
FAQ
Prompt management questions, answered
Prompt management-also called prompt versioning-is a central library for the prompts your applications use. You author each prompt's messages, template variables, and model settings in one place, and every change is tracked as a version, so your team works from a single, reviewable source of truth instead of prompts scattered across code and documents.
Each time you save changes to a prompt, FastRouter creates a new version rather than overwriting the previous one. You get a visual diff of what changed before committing, a full history of every version with who edited it and when, and the ability to restore any earlier version at any time.
Yes. You can select any two versions and view them in a side-by-side comparison, with added lines highlighted in green and removed lines in red. This makes it easy to see exactly what an edit changed before you promote it.
Yes. Because every version is preserved, you can roll back to an earlier version in one click if a change doesn't perform the way you expected-no need to manually reconstruct an old prompt from memory.
Prompt management is integrated with FastRouter's GEPA prompt optimization. You can launch an optimization run from a prompt, and the improved prompt is saved back as a new version. From there you can diff it against the prior version, compare results, and promote it like any other change.
Yes. Prompts support reusable template variables-such as company, tone, or ticket-so a single prompt adapts to each request. Variables are part of the prompt definition and are versioned alongside the rest of the prompt.
Give your prompts a version history
Create your first prompt, iterate with confidence, and optimize with GEPA-all in one versioned library.