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Synthetic Provider Guide

Synthetic is a Tier-2 catalog provider: OpenAI-wire-compatible with no behavioural quirks declared, so its entire integration is one JSON file (src/lib/providers/catalog/synthetic.json) rather than hand-written code. That file is the source of truth for everything on this page.

Verification status: this entry is docs- and roster-verified, not yet live-verified. Every model id, context window, output ceiling and price below comes from an unauthenticated GET /openai/v1/models call plus the vendor's own pricing page and LiteLLM's third-party provider page — no API key was used or is required to onboard this entry. Nobody has yet run a live capability sweep (chat, streaming, tool calls, structured output) against Synthetic with a real key; evidence.liveMatrix is null until that happens. Treat capabilities.tools, .structuredOutput and .thinking as "documented by the vendor," not "wire-proven."

Key Facts​

  • Provider id: synthetic
  • Protocol: OpenAI-compatible (/chat/completions — the only operation LiteLLM's provider page lists for Synthetic)
  • Base URL: https://api.synthetic.new/openai/v1
  • Default model: syn:large:text (deepseek-ai/DeepSeek-V4.1-Flash)
  • Models in catalog: 11 ids covering 7 unique always-on models (short syn:* aliases and full Hugging Face weight ids both resolve)
  • Streaming: documented (vendor docs show a streaming SDK example)
  • Tool calling: documented — every model on the live roster lists tools in supported_features
  • Structured output: documented — every model lists json_mode and structured_outputs in supported_features. Tools + structured output together has not been probed, so structuredOutputWithTools is false until a live combined request confirms it.
  • Reasoning / thinking: documented — every model lists reasoning in supported_features with an explicit reasoning_parameters.efforts list (e.g. none/low/high/xhigh/max)
  • Embeddings: not exposed through this catalog entry. Synthetic's pricing page separately lists an included embedding model (hf:nomic-ai/nomic-embed-text-v1.5), but NeuroLink's embed() / embedMany() surface is currently wired only for OpenAI, Google AI Studio, Google Vertex and Amazon Bedrock — not generic Tier-2 catalog providers — so capabilities.embeddings is false here regardless.
  • Billing: no free tier — flat-fee subscription ($1/day or $30/month, 500 requests/5hr) or enterprise usage-based pricing
  • Key format: none documented

Quick Start​

1. Get an API key​

  1. Visit: https://synthetic.new and choose Sign up (or Log in if you already have an account)
  2. Subscribe to a Pack ($1/day or $30/month, 500 requests/5hr per the pricing page) or set up enterprise usage-based billing — Synthetic has no free tier or keyless trial
  3. Generate an API key from your account dashboard
  4. Set SYNTHETIC_API_KEY in your .env file

2. Configure​

export SYNTHETIC_API_KEY=your-api-key
export SYNTHETIC_MODEL=syn:large:text      # optional — overrides the default model
export SYNTHETIC_BASE_URL=https://api.synthetic.new/openai/v1   # optional — proxy or self-hosted gateway

3. Use it​

import { NeuroLink } from "@juspay/neurolink";

const neurolink = new NeuroLink();

const result = await neurolink.generate({
  input: { text: "Explain context windows in one paragraph." },
  provider: "synthetic",
  model: "syn:large:text",
});

console.log(result.content);
# CLI
npx @juspay/neurolink generate "Hello" --provider synthetic

Per-request credentials work as they do for every provider:

await neurolink.generate({
  input: { text: "Hello" },
  provider: "synthetic",
  credentials: { synthetic: { apiKey: process.env.SYNTHETIC_API_KEY } },
});

Models​

ModelContextMax outVision$/M in · out · cached-inNotes
syn:large:text ⭐512K64Kyes$0.60 / $1.20 / $0.03Recommended — alias for deepseek-ai/DeepSeek-V4.1-Flash. Vendor: "an efficient near-Fable model with vision."
syn:small:text192K64Kno$0.10 / $0.50 / $0.02Alias for zai-org/GLM-4.7-Flash — smaller/faster, ~30B class; text-only input.
syn:large:vision512K64Kyes$3.00 / $15.00 / $0.45Alias for moonshotai/Kimi-K3 — 2.8T-parameter flagship; the most expensive model in the roster.
syn:small:vision256K64Kyes$0.45 / $2.20 / $0.09Alias for Qwen/Qwen3.8-27B — small coding + vision model.
hf:zai-org/GLM-5.3-Flash512K64Kyes$0.15 / $0.50 / $0.04No syn: short alias. Vendor: "an extremely efficient, Opus-4.8-equivalent model with vision."
hf:openai/gpt-oss-120b128K64Kno$0.10 / $0.10 / $0.02OpenAI's open-weight gpt-oss-120b; strong reasoning + agentic use.
hf:nvidia/NVIDIA-Nemotron-3-Super-120B-A12B-NVFP4256K64Kno$0.30 / $1.00 / $0.06Fast 120B model, good for coding agents.
hf:deepseek-ai/DeepSeek-V4.1-Flash512K64Kyes$0.60 / $1.20 / $0.03Same underlying model as syn:large:text, addressed by its full weights id.
hf:moonshotai/Kimi-K3512K64Kyes$3.00 / $15.00 / $0.45Same underlying model as syn:large:vision.
hf:Qwen/Qwen3.8-27B256K64Kyes$0.45 / $2.20 / $0.09Same underlying model as syn:small:vision.
hf:zai-org/GLM-4.7-Flash196K64Kno$0.10 / $0.50 / $0.02Same underlying model as syn:small:text.

All 11 ids and their pricing/context/output figures come directly from the unauthenticated GET /openai/v1/models response (HTTP 200, 2026-09-28); the $/M figures are the roster's per-token USD prices multiplied by 1,000,000. syn:* short aliases and their hf:* full-weights-id equivalents are the same served model with identical specs and pricing — both forms are valid values for model, so both are kept in the catalog.

Fallback order when the default is unavailable: syn:small:text → syn:large:vision → syn:small:vision → hf:zai-org/GLM-5.3-Flash → hf:openai/gpt-oss-120b → hf:nvidia/NVIDIA-Nemotron-3-Super-120B-A12B-NVFP4 → hf:deepseek-ai/DeepSeek-V4.1-Flash → hf:moonshotai/Kimi-K3 → hf:Qwen/Qwen3.8-27B → hf:zai-org/GLM-4.7-Flash.

Verification status​

Tier-2 onboarding requires evidence before a provider is accepted, and pnpm run verify:provider-onboarding gates it in CI. This is what the catalog records for Synthetic — all credential-free:

ProbeResult
Rosterunauthenticated GET /openai/v1/models, HTTP 200, 11 models, 2026-09-28. No API key used or required for this endpoint.
Billingunauthenticated GET https://synthetic.new/pricing, HTTP 200, 2026-09-28 — no free tier; $1/day or $30/month subscription pack (500 req/5hr), or enterprise usage-based pricing.
Third-party wire checkLiteLLM's Synthetic provider page confirms base URL https://api.synthetic.new/openai/v1, env var SYNTHETIC_API_KEY, and /chat/completions as the only supported operation.
Live capability sweepNot yet run. evidence.liveMatrix is null. Tool calling, structured output, streaming and the tools+schema combination are documented by the vendor's own supported_features roster field, not wire-proven against a real key.

Because no live key was used, capabilities.structuredOutputWithTools is false per Tier-2 policy — a documented individual capability is not evidence for the combined one. A future pass with a real SYNTHETIC_API_KEY should run the live matrix (npx tsx test/continuous-test-suite-provider-matrix.ts --provider=synthetic) and update evidence.liveMatrix accordingly.

Troubleshooting​

SymptomCauseFix
Auth error on first requestNo documented auth-error shape yet (no live probe)Check SYNTHETIC_API_KEY is set and valid; see https://synthetic.new for key management
Model not foundThe roster changed since 2026-09-28Pick a current id from the unauthenticated GET /openai/v1/models roster
No free tierSynthetic requires a paid Pack or usage-based billingSubscribe at https://synthetic.new before making live calls
Structured output + tools together failsNot yet probed combined; declared unsupported (structuredOutputWithTools: false) until proven liveSend tools and response_format in separate requests until this is live-verified

See also​