DeepSeek API

DeepSeek API is the first-party inference service from Chinese AI lab DeepSeek (deepseek.com), offering its open-weight frontier models through an OpenAI- and Anthropic-compatible HTTP interface. As of mid-2026 the current models are deepseek-v4-flash (cost-optimized, non-thinking and thinking modes) and deepseek-v4-pro (flagship reasoning), with the legacy deepseek-chat and deepseek-reasoner names kept as compatibility aliases routing to V4 Flash and scheduled for deprecation on 2026-07-24. The headline differentiator is price: V4 Flash runs about $0.14 per million input tokens (cache miss) and $0.28 output, with cache hits as low as $0.0028/M, roughly 90-95% cheaper than comparable OpenAI or Anthropic models, alongside a 1M-token context window and up to 384K output tokens. Because the API mirrors the OpenAI ChatCompletions schema, migration is effectively a two-line change and any OpenAI SDK works without a DeepSeek-specific package.

The product is aimed at cost-sensitive developers, RAG and agent builders, and teams that want frontier-ish reasoning and coding quality at commodity prices, plus those who value being able to self-host the same open weights as a fallback. On quality, DeepSeek V4 Pro lands near the top of open-weight reasoning models on the Artificial Analysis Intelligence Index (~44, #2 among open-weight reasoners behind Kimi K2.6) and posts strong coding/knowledge numbers (e.g. ~80.6% SWE-bench, 87-91% MMLU-Pro depending on mode), though some V4 figures are vendor-reported and await fuller third-party reproduction. Built-in automatic context caching (with explicit prompt_cache_hit/miss token accounting), JSON output, function/tool calling, and FIM completion round out a genuinely capable feature set.

The major weaknesses are operational and trust-related. DeepSeek uses dynamic, load-based rate limiting with no purchasable tier to raise it: under heavy platform load you get HTTP 429s that demand exponential backoff with jitter, and first-party throughput/latency on Artificial Analysis (DeepSeek-hosted V4 Flash ~106-124 t/s, with high time-to-first-token in reasoning mode) trails several third-party hosts like Makora, Together, and Azure. Reliability has been inconsistent, and the bigger blocker for many enterprises is data governance: data is processed on servers in China, which triggered regulatory bans (Italy's Garante, multiple government device bans) and persistent security/privacy criticism. For non-sensitive workloads where price-per-token dominates, it is compelling; for regulated or latency-critical production, many teams route the same open weights through a Western host instead.