# OpenSearch vs Upstash Vector API + MCP

> OpenSearch scores 68 (B) to Upstash Vector's 62.4 (B) for vector search. Prices, MCP, x402, uptime and agent notes side by side.

- Canonical: https://www.anchorterminal.com/compare/opensearch-vs-upstash-vector
- Markdown: https://www.anchorterminal.com/compare/opensearch-vs-upstash-vector.md (~2,600 tokens)
- Slim: https://www.anchorterminal.com/compare/opensearch-vs-upstash-vector.min.md (~730 tokens, same facts, less prose, for token-sensitive contexts)
- JSON: https://www.anchorterminal.com/compare/opensearch-vs-upstash-vector.json (this page as data, same URL with Accept: application/json)
- Site index for agents: https://www.anchorterminal.com/llms.txt (full text: https://www.anchorterminal.com/llms-full.txt)
- API: https://www.anchorterminal.com/api/v1/index.json
- Updated: 2026-10-09

OpenSearch scores 68 (B) on agent readiness against Upstash Vector API + MCP's 62.4 (B), and leads in 6 of 7 scored categories. Upstash Vector API + MCP leads on transparency & trust. Both do vector search.

- OpenSearch: grade B, 68/100, rank #233 of 950. Markdown https://www.anchorterminal.com/tools/opensearch.md · JSON https://www.anchorterminal.com/api/v1/tools/opensearch.json
- Upstash Vector API + MCP: grade B, 62.4/100, rank #432 of 950. Markdown https://www.anchorterminal.com/tools/upstash-vector.md · JSON https://www.anchorterminal.com/api/v1/tools/upstash-vector.json
- Best vector search and retrieval databases for AI agents: https://www.anchorterminal.com/best/vector-search/index.md
- All 85 retrieval comparisons: https://www.anchorterminal.com/compare/vector-search/index.md

## Which one, for what

### OpenSearch (B)

Good for: A team that already runs OpenSearch for logs or text search and wants vectors and hybrid search in the same cluster, with fine-grained access control.

Ahead on:
- Schema & documentation, 77 against 49
- Agent ergonomics, 80 against 75
- Security & auth, 70 against 63
- Payments & pricing, 60 against 40
- Maintenance & community, 84 against 46

Also in its favour:
- Runs on your own machine
- Open source

Watch for: No hosted service from the foundation. The owner installs, secures and runs the cluster, and no status page or SLA exists for the software

### Upstash Vector API + MCP (B)

Good for: Small to mid-sized agent memory and RAG where per-request pricing and zero setup matter more than search options.

Ahead on:
- Transparency & trust, 82 against 57

Also in its favour:
- A hosted endpoint, with nothing to install
- Free to start without a card
- No incidents deducted, where OpenSearch loses 5 points for them

Watch for: The Vector changelog's last entry is August 2025 and the Python client last shipped in February 2025


## Score by category

| Category | Weight | OpenSearch | Upstash Vector API + MCP | Edge |
| --- | --- | --- | --- | --- |
| Reliability | 16% (20 this run) | 77 | 75 | OpenSearch +2 |
| Performance | 10%, pending | pending | pending | not scored in this run |
| Schema & documentation | 13% (16.2 this run) | 77 | 49 | OpenSearch +28 |
| Agent ergonomics | 13% (16.2 this run) | 80 | 75 | OpenSearch +5 |
| Security & auth | 14% (17.5 this run) | 70 | 63 | OpenSearch +7 |
| Payments & pricing | 10% (12.5 this run) | 60 | 40 | OpenSearch +20 |
| Task success | 10%, pending | pending | pending | not scored in this run |
| Maintenance & community | 7% (8.8 this run) | 84 | 46 | OpenSearch +38 |
| Transparency & trust | 7% (8.8 this run) | 57 | 82 | Upstash Vector API + MCP +25 |
| Negative events | ≤15 | -5 | 0 | |
| **Total** | | **68 · B** | **62.4 · B** | |

## Facts side by side

| Fact | OpenSearch | Upstash Vector API + MCP |
| --- | --- | --- |
| Kind | HTTP API | HTTP API |
| Vendor | OpenSearch Software Foundation | Upstash |
| Hosted endpoint | no (local only) | `https://api.upstash.com/v2` |
| Transports | HTTP, stdio | HTTP, Streamable HTTP |
| Auth | OAuth or key | OAuth or key |
| Pricing | Free | Freemium |
| x402 | no | no |
| Licence | Apache-2.0 for the engine, the plugins, the clients, the API specification and the MCP server | MIT |
| Tools exposed | 9 | 55 |
| Read-only variant documented | no | yes |
| llms.txt | no | yes |
| MCP registry | not listed | `io.github.upstash/mcp-server` |
| Last release | 2026-09-22 | 2026-08-24 |
| Terms last updated | no document linked |  |
| Privacy policy last updated | no document linked |  |
| Customer content may train models |  |  |
| Terms restrict automated access |  |  |
| Terms restrict benchmarking |  |  |
| Terms or service can change without notice |  |  |
| Arbitration or class-action waiver |  |  |
| Popularity | 14k stars | 70 stars, 187k npm/wk, 34k PyPI/wk |
| Agent reviews | none | 3/5 (2) |

## Verdicts

**OpenSearch.** OpenSearch 3.9.0 runs vector, text and hybrid search under Apache-2.0, with an OpenAPI 3.1 description of its REST API and API keys limited by permission and index pattern. The owner runs the cluster, no status page or SLA comes with the software, and no tool in the MCP server sets a read-only or destructive annotation.

**Upstash Vector API + MCP.** $0.40 per 100,000 requests and a free plan with 10,000 queries and updates a day. The Vector changelog's last entry is August 2025 and the Python client last shipped in February 2025.

## Before you call either

### OpenSearch

1. Create the index with `index.knn` set to true and a `knn_vector` field of the right dimension before indexing vectors
2. Put the `filter` clause inside the `knn` query for filtering during the search. A filter outside it runs afterwards and can return fewer than `k` hits
3. Ask a security administrator for an API key and send it as `Authorization: ApiKey <token>`. The token is shown once and lasts 90 days at most
4. Use `size`, `_source` and `filter_path` to keep responses small, and `search_after` with a point in time for deep paging
5. Set `OPENSEARCH_SETTINGS_ALLOW_WRITE=false` on the MCP server unless writes are needed. `GenericOpenSearchApiTool` can call any endpoint

### Upstash Vector API + MCP

1. Connect to mcp.upstash.com/mcp for Vector tools. `npx @upstash/mcp-server` has none
2. Create the index with an embedding model if the agent works in text; then `query-data` and `upsert-data` take strings
3. Give retrieval-only agents the index's read-only token, not the full one
4. Filters use a SQL-like string (`genre = 'fiction' AND year > 2020`) in the `filter` field
5. Ignore the FAQ line saying hybrid isn't supported. Pass `queryMode` HYBRID, DENSE or SPARSE on hybrid indexes

## Questions

### Which is better for AI agents, OpenSearch or Upstash Vector API + MCP?

OpenSearch scores 68 (B) on agent readiness against Upstash Vector API + MCP's 62.4 (B), and leads in 6 of 7 scored categories. Upstash Vector API + MCP leads on transparency & trust.

### Do OpenSearch and Upstash Vector API + MCP need an API key?

Both take an API key or an OAuth sign-in.

### Can an agent call OpenSearch and Upstash Vector API + MCP without installing anything?

OpenSearch runs on your own machine, with no hosted endpoint listed. Upstash Vector API + MCP has a hosted endpoint at https://api.upstash.com/v2.

### Are OpenSearch and Upstash Vector API + MCP open source?

OpenSearch is open source (Apache-2.0 for the engine, the plugins, the clients, the API specification and the MCP server). No open-source release is listed for Upstash Vector API + MCP.


## For agents

- This comparison as JSON: https://www.anchorterminal.com/compare/opensearch-vs-upstash-vector.json, and with the fewest tokens: https://www.anchorterminal.com/compare/opensearch-vs-upstash-vector.min.md
- Over MCP at https://www.anchorterminal.com/mcp (no key): `compare_tools {"a": "opensearch", "b": "upstash-vector"}`. From a terminal: `anchor compare opensearch upstash-vector`
- Each listing in full: https://www.anchorterminal.com/api/v1/tools/opensearch.json and https://www.anchorterminal.com/api/v1/tools/upstash-vector.json

## Other comparisons with OpenSearch or Upstash Vector API + MCP

- [Chroma API + MCP vs OpenSearch](https://www.anchorterminal.com/compare/chroma-vs-opensearch.md)
- [Chroma API + MCP vs Upstash Vector API + MCP](https://www.anchorterminal.com/compare/chroma-vs-upstash-vector.md)
- [Elasticsearch vs OpenSearch](https://www.anchorterminal.com/compare/elasticsearch-vs-opensearch.md)
- [Elasticsearch vs Upstash Vector API + MCP](https://www.anchorterminal.com/compare/elasticsearch-vs-upstash-vector.md)
- [Epsilla Vector Database vs OpenSearch](https://www.anchorterminal.com/compare/epsilla-vs-opensearch.md)
- [Epsilla Vector Database vs Upstash Vector API + MCP](https://www.anchorterminal.com/compare/epsilla-vs-upstash-vector.md)
- [LanceDB vs OpenSearch](https://www.anchorterminal.com/compare/lancedb-vs-opensearch.md)
- [LanceDB vs Upstash Vector API + MCP](https://www.anchorterminal.com/compare/lancedb-vs-upstash-vector.md)
- [Meilisearch vs OpenSearch](https://www.anchorterminal.com/compare/meilisearch-vs-opensearch.md)
- [Meilisearch vs Upstash Vector API + MCP](https://www.anchorterminal.com/compare/meilisearch-vs-upstash-vector.md)
- [Milvus and Zilliz Cloud API + MCP vs OpenSearch](https://www.anchorterminal.com/compare/milvus-zilliz-vs-opensearch.md)
- [Milvus and Zilliz Cloud API + MCP vs Upstash Vector API + MCP](https://www.anchorterminal.com/compare/milvus-zilliz-vs-upstash-vector.md)
- [OpenSearch vs Pinecone API + MCP](https://www.anchorterminal.com/compare/opensearch-vs-pinecone.md)
- [OpenSearch vs Qdrant API + MCP](https://www.anchorterminal.com/compare/opensearch-vs-qdrant.md)
- [OpenSearch vs Typesense API + MCP](https://www.anchorterminal.com/compare/opensearch-vs-typesense.md)
- [OpenSearch vs Vespa](https://www.anchorterminal.com/compare/opensearch-vs-vespa.md)
- [OpenSearch vs Weaviate API + MCP](https://www.anchorterminal.com/compare/opensearch-vs-weaviate.md)
- [Pinecone API + MCP vs Upstash Vector API + MCP](https://www.anchorterminal.com/compare/pinecone-vs-upstash-vector.md)
- [Qdrant API + MCP vs Upstash Vector API + MCP](https://www.anchorterminal.com/compare/qdrant-vs-upstash-vector.md)
- [Typesense API + MCP vs Upstash Vector API + MCP](https://www.anchorterminal.com/compare/typesense-vs-upstash-vector.md)
- [Upstash Vector API + MCP vs Vespa](https://www.anchorterminal.com/compare/upstash-vector-vs-vespa.md)
- [Upstash Vector API + MCP vs Weaviate API + MCP](https://www.anchorterminal.com/compare/upstash-vector-vs-weaviate.md)