What OpenRouter is
OpenRouter gives you one API key and one endpoint for hundreds of models across providers, with per-token pricing and easy model switching. For inference workloads (chat products, agents, summarization pipelines, model comparison for generative quality) it's an excellent piece of infrastructure, and if that's your workload you should use it.
It's deliberately unopinionated. OpenRouter returns what the model returns: prose. What you do with that prose is your code, which is exactly the flexibility inference customers want.
What MentionsAPI is
MentionsAPI is opinionated in the opposite direction. One call takes a query and a brand and returns structured JSON: mentioned or not, rank within the answer, cited URLs, per surface. The prompt handling, brand matching, and citation parsing are inside the API. You can't use it to build a chatbot, and that's the point.
It ships as a REST API plus a remote MCP server at api.mentionsapi.com/mcp, so agent workflows can call it as a tool without any HTTP glue.
Building brand monitoring on OpenRouter yourself
Here's the honest bill of materials. You'd write: a prompt set and fan-out logic per model, a brand matcher that survives casing and alias variants, rank computation within answers, citation extraction across each model's format, caching so repeat queries don't burn tokens, and scheduling plus storage for trend lines. None of it is exotic. All of it is maintenance, because model output formats and behaviors shift under you.
If brand monitoring is your core product and you want full control over every layer, building on raw inference is a legitimate choice. If it's a feature in a bigger product, or you'd rather spend the engineering elsewhere, one purpose-built endpoint replaces that whole list.
The wall: surfaces that aren't model APIs
There's a category of AI surface that no inference API can reach, because they aren't models you can route to. Google AI Overviews, Google AI Mode, and Bing Copilot are rendered products; what chatgpt.com shows a logged-in user differs from what the OpenAI API returns. You cannot check those surfaces through OpenRouter, no matter how much glue code you write, because there's no model endpoint behind them to call.
MentionsAPI's *_live modes check the rendered surfaces directly: AI Overviews (15 credits), AI Mode (35), Bing Copilot (15), and the live ChatGPT (35), Gemini (35), and Perplexity (85) UIs, with `mode: all_live` sweeping everything for 165 credits. If your monitoring needs to reflect what users actually see, this is the difference that decides the comparison.
Pricing models and which to pick
OpenRouter bills per token, which is the right model for inference: costs scale with usage and you choose the model tier per call. MentionsAPI bills fixed credits per check from a wallet: 300 free one-time on signup, $5/mo for 1,000 credits or $54/yr for 12,000, top-ups at $4 per 1,000 (monthly) or $3 per 1,000 (annual), credits never expire. A quick check is 130 credits fresh, 5 cached.
Pick OpenRouter for anything generative: chat products, agents, content pipelines, model experimentation. Pick MentionsAPI when the job is measurement: is the brand visible, where, with what citations, across API and live surfaces. Plenty of stacks run both, inference through OpenRouter and visibility checks through us, because the two never overlap in what they do.