openaideepseekmigration
Migrating from OpenAI to DeepSeek: A 5-Minute Guide
June 8, 2026
If you are using the OpenAI SDK, migrating to DeepSeek V4 Pro takes exactly one line change. This guide covers Python, Node.js, environment variable configuration, and how to verify the switch works correctly.
Step 1: Get Your API Key
Sign up at nex-api.tech, go to Dashboard → API Keys, and create a key. It starts with napi-.
Step 2: Change One Line
Python
# Before (OpenAI)
client = OpenAI(api_key='sk-...')
# After (NexAPI + DeepSeek)
client = OpenAI(
base_url="https://nex-api.tech/v1",
api_key="napi-..."
)
client = OpenAI(api_key='sk-...')
# After (NexAPI + DeepSeek)
client = OpenAI(
base_url="https://nex-api.tech/v1",
api_key="napi-..."
)
Node.js
// Before (OpenAI)
new OpenAI(apiKey: process.env.OPENAI_API_KEY)
// After (NexAPI + DeepSeek)
new OpenAI({
baseURL: "https://nex-api.tech/v1",
apiKey: process.env.NEXAPI_KEY
})
new OpenAI(apiKey: process.env.OPENAI_API_KEY)
// After (NexAPI + DeepSeek)
new OpenAI({
baseURL: "https://nex-api.tech/v1",
apiKey: process.env.NEXAPI_KEY
})
Step 3: Verify It Works
Run a quick test:
response = client.chat.completions.create(
model="deepseek-v4-pro",
messages=[{"role":"user","content":"Say hello in one word"}]
)
print(response.choices[0].message.content)
model="deepseek-v4-pro",
messages=[{"role":"user","content":"Say hello in one word"}]
)
print(response.choices[0].message.content)
What Works Out of the Box
- Chat completions — exactly the same API
- Streaming — identical SSE format
- Function calling / Tools — same schema
- System prompts — fully supported
- Temperature, max_tokens, top_p — all identical
- JSON mode — response_format works
Cost Comparison
| Scenario | OpenAI GPT-4o | NexAPI DeepSeek | Savings |
|---|---|---|---|
| 100K tokens/day | $7,500/mo | $840/mo | 89% |
| 1M tokens/day | $75,000/mo | $8,400/mo | 89% |
| 10 calls/day | $2.50/mo | $0.28/mo | 89% |