Yesterday I stumbled on a tool that scratches an itch every prompt engineer has felt at 2am: which model actually gives the best answer for the least money, without the five-tab juggling act most of us put ourselves through to find out. You know the drill. One tab for ChatGPT, one for Claude, one for Gemini, maybe a fourth for whatever open source model you’re curious about that week, and you’re copy-pasting the same prompt into each one, trying to remember which answer came from where. RouterDash is a free prompt playground that fires the same prompt at multiple models and providers at once and shows you the answers side by side, no tab switching required. It comes from u/AndyMagill, a Redditor who built it to solve his own testing headache and figured the rest of us were dealing with the same problem, which is usually how the best tools get made.
Here’s the twist. RouterDash isn’t locked to one API. It pulls from OpenRouter, Groq, and Cerebras, so you’re not just comparing GPT against Claude, you’re comparing how fast and cheap each provider serves the same model. That’s the part most playgrounds skip. Cost and latency matter as much as raw quality when you’re picking what to ship, and this tool puts all three in front of you at the same time, in the same window. Groq and Cerebras in particular are worth watching here because they’re both chasing raw inference speed, so seeing their numbers next to OpenRouter’s broader model catalog gives you a much fuller picture than any single provider’s own playground would.
The other detail worth flagging: everything runs client side. Your prompts and API keys stay in your browser’s local storage, nothing gets shipped to a server you don’t control. For anyone testing prompts with sensitive data or client work, that’s not a small feature: it’s the reason to actually use it. A lot of playground tools ask you to trust a backend you can’t see, and half the time you don’t even know where your test prompts end up living. This one just doesn’t have one to worry about. If you’ve ever hesitated before pasting a client’s internal doc into some random web tool to test a prompt, this removes that hesitation entirely.
How the workflow looks in practice:
- 🔑 Drop in your API keys for OpenRouter, Groq, or Cerebras, whichever you have on hand. You don’t need all three to start, even one gets you multi-model comparisons within that provider.
- 📝 Write your prompt once, or pull from one of the built-in templates if you’re not sure where to start.
- Attach an image if you’re testing a vision task, that’s a recent addition to the tool, and it’s a good way to stress test how different models handle the same visual input.
- ⚡ Send it to multiple models at once and watch the responses stack up in real time, side by side, so you can actually scan for differences instead of scrolling between tabs.
- 💰 Compare cost and speed alongside quality to find your cheapest “good enough” option, which is usually the number that actually decides what ships to production.
The author mentioned using this exact workflow to find the cheapest high-quality model for a separate project, and that’s honestly the best use case for a tool like this. You’re not chasing the smartest model on the leaderboard, you’re chasing the cheapest one that still gets your specific job done well enough to ship. That distinction matters more than people admit. Most production tasks don’t need the top-tier flagship model, they need a model that’s good enough, fast enough, and cheap enough to run at scale without blowing your budget.
Pro tip: run your actual production prompt through this, not a generic test question. Model rankings shift wildly depending on task type, a model that wins on creative writing can lose badly on structured extraction. Test with the real thing, not a warm-up question, and ideally test with a handful of real examples rather than just one, since a single lucky output can be misleading.
Pro tip: since your keys never leave the browser, this is safe to use for prompts tied to client or business data. Just don’t share your screen while your keys are visible in the settings panel, and if you’re on a shared computer, clear local storage when you’re done.
One caveat straight from the source: if your workflow depends on chaining multiple prompts together, this tool wasn’t built with that in mind. The creator said as much in the comments, someone doing multi-step agent chains probably won’t get much use out of it. It’s made for single-shot comparisons, not multi-step pipelines. Know that going in and you’ll get exactly what you need out of it, no more, no less.
Worth mentioning too: prompt templates and image attachments only landed recently, so this is a tool that’s still actively growing. If there’s a feature you want, the creator is reading the comments, and that kind of open feedback loop is worth taking advantage of while it’s fresh.
If you’ve used OpenRouter’s own playground before, this feels similar on the surface but takes a different angle. OpenRouter’s interface is built to showcase OpenRouter. RouterDash treats providers as interchangeable, Groq and Cerebras sit right next to OpenRouter models with no home-team bias, which makes it a more honest place to shop for the cheapest option that still holds up on quality.
If you’re tired of guessing which model to use before you’ve even started building, go try RouterDash and see what the same prompt looks like across three providers at once. Then swing by the original Reddit thread and tell the creator what you’d want added next. 🚀
Frequently Asked Questions
Q: Is RouterDash really free? Do I need to pay anything?
Yes, RouterDash itself is completely free. You’ll need your own API keys for the providers you want to test (OpenRouter, Groq, Cerebas), and you pay based on your actual usage through those services. RouterDash doesn’t add any markup or hidden costs.
Q: How does RouterDash keep my data private?
Everything runs directly in your browser using local storage, your API keys, prompts, and comparison results never leave your computer. There’s no server backend, so you have complete privacy and control over your data.
Q: Can I use RouterDash for testing complex multi-prompt workflows?
RouterDash is optimized for comparing single prompts across different models and providers to find the best cost-quality balance. If you need to test complex, interdependent multi-prompt sequences, you might need additional tools, but it’s excellent for evaluating individual prompt performance.
Q: What can I do with the new prompt templates and image attachments?
Templates help you get started faster with pre-built prompts you can customize, while image attachment support lets you test vision models and see how different providers handle image inputs differently.
I made RouterDash, a free Prompt Playground to compare models & providers
by u/AndyMagill in PromptEngineering