Test any model. Right from your browser.
An interactive playground for 97+ models. Chat, tweak parameters, compare responses, watch cost + latency in real time, and export integration code in 15 languages — without writing a single line of integration code.
Active session
- Server-side key storage
- 0
- Models you can test
- 97+
- Streaming + non-stream
- Both
- Code-gen languages
- 15
Your key lives in sessionStorage only
Anthropic, Google & OpenAI
Real-time tokens or full-response mode
8 SDKs + 7 frameworks
Chat, swap models, watch the cost — per message.
The customer reports a billing mismatch after upgrading mid-cycle. Suggested tone: empathetic and direct — confirm the proration math first, then offer the credit…
218 tokens · $0.0008 · TTFT 120 ms
The same path as production — no sandboxing
Every playground request uses your real virtual key and traverses the same auth, credit-reserve, guardrail, and provider chain as your SDK. No fake responses, no mock providers, no silent shortcuts.
Playground request flow
Paste key
sessionStorage only
Cleared on tab close; never sent to Nemo Router servers.
Frontend (Next.js)
Cloud Run
Forwards request with the user-pasted virtual key.
Nemo Backend
Nemo Router
Auth, credit reserve, guardrails — same as production.
Nemo Intelligent Proxy Router
Routing engine
Cost tracking, rate limits, provider fallback.
Provider
Vertex / Anthropic / OpenAI
Real LLM call — no sandboxing, no fake responses.
Your key never leaves the browser
Virtual key only
sessionStorage scope, master key isolated
Every LLM call — playground, SDK, or production API — must authenticate with a virtual key (sk-nemo-...). The playground enforces this by holding the key only in browser sessionStorage. Refresh the tab and you re-paste; close the tab and the key is gone.
- Browser sessionStorage scope (cleared on tab close)
- Never POSTed to Nemo Router for persistent storage
- Master key never enters the playground flow
- Per-key spend, RPM, TPM enforced exactly as in production
Storage + auth posture
Full playground reference — chat, streaming, parameters, code-gen
- Full chat interface
- System prompts, multi-turn history, model swap mid-conversation, and a side-by-side compare model. Latest-response tokens, cost, and latency in the Metrics tab. Cancel mid-stream to stop token spend.
- Streaming + non-streaming
- SSE streaming (default) with a live token-rate counter, or full-response mode for batch / eval workflows. Identical billing — both modes use the same pipeline.
- Parameter pass-through
- temperature, top_p, max_tokens, and a system prompt — every parameter you set is forwarded as-is to the provider, with no silent defaults.
- Code generation — 15 languages
- Python (native + OpenAI-compatible), Node.js, Go, Ruby, Java, PHP, cURL, plus 7 frameworks (LangChain, LlamaIndex, CrewAI, AutoGen, Google ADK, more). Drawn from the canonical SDK examples package — embeds your exact prompt + parameter set.
- Error surfacing
- 402 (out of credits) surfaced with an inline top-up CTA. 429 with a retry-after timer. Provider 4xx errors shown verbatim. Streaming aborts cleanly on mid-stream errors.
- Model catalog access
- Every model in your account, one dropdown. Filter by capability (chat, vision, embedding, image, video), provider, latency budget, or cost ceiling. Switch models mid-conversation; price-per-1k tokens visible per model.
Common playground questions
97+ models · 15 code generators · 0 server-side keys
From idea to working prototype in under a minute
No SDK to install, no provider account to manage. Sign up, paste your virtual key, start chatting.