Here we research popular, currently well-supported keyword extraction APIs, compare their features, free tier options, underlying technology, and **long-term viability** (to the extent possible).
# Recommendation If **long-term stability** is your main concern, and you want a managed service: - **Google Cloud** or **Azure** are the safest, with consistent support and generous free tiers. - **AWS** is also stable but the free period is time-limited. - **IBM Watson** is a good alternative, less popular but not going anywhere soon. If you want **full control and never worry about API shutdown**, consider running spaCy on your own server. This is more technical, but avoids vendor risk entirely.
- Google Natural Language API - Azure Text Analytics API and Amazon Comprehend API - Watson Natural Language API
# Summary Table | Service | Free Tier | Quality | Underlying Tech | Stability & Support | Notes | | ------------------- | --------------- | ------- | -------------------- | ------------------- | ------------------------ | | Google NLP | Yes (5,000/mo) | Top | Proprietary DL/ML | Very High | Expensive at scale | | Azure Text | Yes (5,000/mo) | Top | Proprietary DL/ML | Very High | Good docs | | AWS Comprehend | Yes (50k/3mo) | Strong | Proprietary DL/ML | Very High | Free tier short-lived | | Aylien | Yes (1,000/mo) | Good | ML + rules | Moderate | Small, but stable so far | | MonkeyLearn | Yes (300/mo) | Good | ML/NLP | Moderate | No “giant” backing | | IBM Watson NLU | Yes (30,000/mo) | Strong | Proprietary DL/ML | High | Slightly dated | | OpenAI (GPT) | No | Top | GPT-4o | Very High | Prompt-based, pricey | | spaCy (self-hosted) | Unlimited (OSS) | Top | spaCy + transformers | Very High | You host; full control |