Head to head · Web search · October 2026 research run

Grounding with Bing Search vs Kagi Search API

Grounding with Bing Search scores 63.7 (B) on agent readiness against Kagi Search API's 56.1 (C), and leads in 3 of 7 scored categories. Kagi Search API leads on agent ergonomics and transparency & trust. Both do web search. Kagi Search API is cheaper for web search, $12 against $14 per 1,000 requests.

Best web search APIs for AI agents · All 308 search comparisons

Which one, for what

Grounding with Bing Search B

Best for Teams already building on Foundry Agent Service who want cited answers from Bing without handling a search key.

Ahead on

  • Reliability, 68 against 43
  • Security & auth, 79 against 64
  • Maintenance & community, 80 against 41

Watch for

The Bing tools never return raw results to developers, only a model-written answer with citation links

Kagi Search API C

Best for An owner who already pays for Kagi and wants its ranking, lenses and domain rules inside an agent, with page text in the same call.

Ahead on

  • Agent ergonomics, 75 against 61
  • Transparency & trust, 74 against 66

Also in its favour

  • Cheaper for web search, $12 against $14 per 1,000 requests
  • Runs on your own machine

Watch for

Public preview since 21 May 2026. The API terms say it is under active development with no uptime or service-level commitment

Why the edge

Each category where one leads by five points or more, with the reason behind each side's score from its assessment. The numbers are in the table below; this is what they stand for.

Maintenance & community Grounding with Bing Search +39

Grounding with Bing Search 80

Read as a closed service with official SDKs, as the other Azure listings are. The web search page was updated on 2 November 2026 and the Bing tools page on 12 October, and azure-ai-projects 2.10.0 shipped on PyPI and npm on 30 October 2026, the SDK that carries the tool types (30). azure-ai-projects released 2.6.0 (4 September), 2.6.1, 2.7.0, 2.8.0 (5 October), 2.9.0 (17 October) and 2.10.0 in the 90 days from 8 August. Their changelogs weren't read for web search changes, so they count as SDK releases (20). Microsoft Learn feedback, Microsoft Q&A and the Azure SDK issue trackers, whose reply times weren't sampled (10 of 15). Current official SDKs in Python, JavaScript, .NET and Java, the .NET one in preview (15). The SDKs live in the azure-sdk monorepos and CI wasn't checked (5 of 10). 30 + 20 + 10 + 15 + 5 = 80.

Kagi Search API 41

The last dated API change is the Extract API fix in the changelog post of 21 August 2026, 75 days before this check. The posts of 10 September and 16 October carry no API item (20). That is the only dated API entry in the 90 days from 6 August (0). The MCP server's repository gained commits on 27 and 28 October 2026 (compact JSON results, readOnlyHint, per-page extraction errors) and a version bump to 1.1.0 with no tag, so no release is shown; PyPI didn't resolve for us. A public changelog that credits user reports, developers@kagi.com, a Discord #api forum and GitHub discussions. We could not read the issue list, since the GitHub API answered 403 (9). Four generated clients last synced on 26 May 2026, Python tagged only as 1.0.0rc3, TypeScript not on npm on 9 October, and kagimcp tagged last as v0.1.5 (8 April 2026). We did not look the server up in the MCP registry (8). The Python client has a generated CI workflow and the MCP server has a lock file but no CI workflow (4). 20 + 0 + 9 + 8 + 4 = 41.

Reliability Grounding with Bing Search +25

Grounding with Bing Search 68

Graded on the hosted lines, for the Foundry Agent Service tools agents call. Azure status page with post-incident reviews and a Foundry Agent Service component (20). The history page read on 6 November lists one review in the 90 days from 8 August that names Foundry Agent Service, intermittent failures and latency in Sweden Central from 10:03 to 15:58 UTC on 29 September 2026. It was one region and partial, and the review doesn't name Grounding with Bing, so minor only, the reading the Azure Translator listing got for the same review (20). The pricing page publishes 150 transactions a second and 1 million a day for each Grounding with Bing resource (15). The web search troubleshooting table says to answer 429 with exponential backoff and retries. No Retry-After or tool-specific overload guidance was found, and searches have no side effects (8 of 15). No SLA naming Grounding with Bing was found. The terms make it a First Party Consumption Service apart from the Online Services terms, and the Online Services SLA document wasn't opened (0). Grounding with Bing Custom Search is marked preview and Grounding with Bing Search is not, but no page read states general availability for it or for the web_search tool, and the .NET SDK is in preview (5 of 10). 20 + 20 + 15 + 8 + 0 + 5 = 68.

Kagi Search API 43

Status page at status.kagi.com (Instatus), found through a web search on 4 November, with a Kagi API group of nine regional components such as [API] us-east4 and [API] europe-west2, and history back to 2025 (20). In the 90 days from 6 August its feed and incident list show [API] incidents on single regions only. us-central1 on 12 September (1 hour 3 minutes), 19 September, 12 October and 19 October (2 to 3 minutes each), europe-west2 on 19 October (1 minute) and 20 October (8 hours 11 minutes, the region taken out of the global load balancer), asia-east2 on 30 September (4 minutes), australia-southeast1 on 11 September (1 minute) and asia-southeast1 on 7 August (about a minute). Each hit one region of nine, so all read as partial and the record is minor incidents only (20). The six 'API outage' entries (10, 20 and 26 August, two on 14 October and 22 October, 5 to 21 minutes each) name the API component of the Kagi Assistant group, not the Search API, and the 27 September database maintenance had an announced window. No rate limit numbers are published. The terms say only that limits and quotas apply per plan (0). The OpenAPI file documents 429 as 'Rate limited or usage limit exhausted' with no Retry-After header or backoff guidance. The calls are read-only, and Kagi's own MCP server retries 429 and 5xx twice by default (3). The pricing page lists SLAs under Enterprise by quote, and the API terms say there is no uptime or service-level commitment unless agreed in writing (0). The OpenAPI file still describes a preview period (0). 20 + 20 + 0 + 3 + 0 + 0 = 43.

Security & auth Grounding with Bing Search +15

Grounding with Bing Search 79

Callers authenticate to the Foundry project with Microsoft Entra ID tokens and RBAC roles (Foundry User to run agents, Foundry Project Manager to add connections), with just-in-time Contributor through Entra PIM for provisioning. The Bing resource key sits in a project connection and the agent never holds it. No key in a URL (28 of 30). The tools only read. Custom Search confines grounding to configured public domains, and an admin can turn web search off for a whole subscription. There is no per-agent read-only toggle to set, since the tools have no write path (15 of 20). The web search page tells developers to treat web search results as untrusted input and to keep secrets and personal data out of prompts, and the tool best practices page says the same of all tool outputs. Raw results are not passed back to the caller (10 of 15). Run steps show each tool call and the Bing query sent, and Azure's activity log covers resource changes. No per-query audit log for Bing was found (10 of 15). Microsoft runs a coordinated vulnerability disclosure policy and bounty programmes through MSRC. microsoft.com's security.txt passed its Expires date on 23 September 2026 and still carries it on 6 November, and the Azure compliance attestations are not shown to cover a service whose data leaves the compliance boundary (16 of 20). 28 + 15 + 10 + 10 + 16 = 79.

Kagi Search API 64

Several named keys an account, each limited to chosen products and optionally to IP addresses or ranges, revoked by deleting. The v1 key travels only in the Authorization header. No expiry or OAuth (27). The API only reads. Per-key product limits and a spending cap in USD narrow what a leaked key can do (16). Search and Extract return third-party page text, and we found no prompt-injection guidance in the reference, the docs or the MCP README (2). The portal shows use count and last-used time per key and requests and cost per day per API, and every response carries a trace ID. No per-call log (7). security.txt with a contact, a bug bounty with a safe harbour policy, and an independent audit by Illumant cited on the security page, whose date we did not read. No SOC 2 or ISO 27001 statement found. security.txt re-read on 4 November (12). 27 + 16 + 2 + 7 + 12 = 64.

Agent ergonomics Kagi Search API +14

Grounding with Bing Search 61

Read as a server-side search tool inside an agent run. The tools return a model's answer with citations rather than raw results, and search_context_size sets how much context web search uses. A caller can't size or inspect the result set itself, since the Bing tools never return their output. Custom Search confines grounding to chosen domains without code (18 of 25). count, freshness, market and language filters, and domain restriction through Custom Search. No pagination or offset (13 of 20). Troubleshooting tables give causes and fixes for connection ID, RBAC and 429 problems, but the tools document no error codes (8 of 20). Searches only read, so a retry is safe apart from the per-transaction charge. No MCP annotations are documented for the toolbox's web search tool (10 of 20). The web_search route needs only a project, a model deployment and the Foundry User role. bing_grounding also needs a paid Bing resource and a project connection. SDKs in Python, C#, JavaScript and Java (12 of 15). Prompt caching gets no hits with the Bing tools, because they add a timestamp to every request. 18 + 13 + 8 + 10 + 12 = 61.

Kagi Search API 75

limit caps results, extraction of page text is opt-in, snippet length follows an account setting, and an experimental Markdown response format exists. The MCP server has two tools (22). page 1 to 10, limit 1 to 1,024, lens and filters for domains, keywords, file type, dates and region (20). Errors return a namespaced code, a message, the field location and a trace ID, but no code catalogue is published and the linked error pages are not live (12). Both operations are read-only, so a retry is safe, though the docs do not say so and failed-call billing is stated only for extraction. The released MCP server sets no read-only annotations. A commit of 27 October adds readOnlyHint to its source with an untagged 1.1.0 version bump, not yet shown as released (10). Only query is required and defaults are stated. Generated clients exist for Python, TypeScript, Go and Rust, installable from GitHub. @kagi/api returned 404 on npm on 9 October (11). 22 + 20 + 12 + 10 + 11 = 75.

Transparency & trust Kagi Search API +8

Grounding with Bing Search 66

Closed service. The terms of use, updated November 2025, are separate from the Online Services terms and sit under the customer's Microsoft agreement (15 of 30). The docs and the terms agree that the Data Protection Addendum and the Product Terms' privacy and security terms don't apply, that Microsoft and the customer are independent controllers, and that the query and parameters leave the Azure compliance and geographic boundary. The terms defer storage and use of query data to the general Microsoft Privacy Statement and state no retention period (15 of 30). The Bing Search APIs retirement was announced on 16 May 2025 for 11 August 2025, under three months' notice, and the web search page marks the Deep Research tool deprecated with a replacement. Microsoft's lifecycle policy covers Azure services, but no deprecation terms for Grounding with Bing were found (10 of 20). Data location for Bing processing isn't stated, and no sub-processor list for it was found (5 of 20). 15 + 15 + 10 + 5 = 45.

Kagi Search API 74

Closed service with clear API terms dated 22 September 2026. The MCP server is MIT and the OpenAPI file states Apache-2.0 (18). The privacy policy's API section agrees with the API terms. Queries are not stored against the account, load balancer and VM logs are kept 7 days and sampled Sentry errors 90 days. The Data Processing Addendum both documents cite is not yet published (23). v0 is marked deprecated with no end date, and the terms promise reasonable notice of breaking changes only where practicable (5). The privacy page names the payment processors and Sentry, the FAQ names GCP as the hosting provider and the docs name search sources, but there is no subprocessor list and no data locations (8). 18 + 23 + 5 + 8 = 54.

Score by category

CategoryWeight this runGrounding with Bing SearchKagi Search APIEdge
Reliability16%206843Grounding with Bing Search +25
Performance10%pendingpendingpendingnot scored in this run
Schema & documentation13%16.26871Kagi Search API +3
Agent ergonomics13%16.26175Kagi Search API +14
Security & auth14%17.57964Grounding with Bing Search +15
Payments & pricing10%12.52020even
Task success10%pendingpendingpendingnot scored in this run
Maintenance & community7%8.88041Grounding with Bing Search +39
Transparency & trust7%8.86674Kagi Search API +8
Negative events≤1500
TotalB 63.7/100C 56.1/100

Facts side by side

FactGrounding with Bing SearchKagi Search API
KindHTTP APIHTTP API
VendorMicrosoftKagi
Hosted endpointhttps://{account}.services.ai.azure.com/api/projects/{project}/openai/v1/responseshttps://kagi.com/api/v1/search
TransportsStreamable HTTPHTTP, Streamable HTTP, stdio
AuthOAuthAPI key
PricingPay per usePay per use
Price for web search$14 per 1,000 requests$12 per 1,000 requests
x402nono
LicenceProprietary service under the customer's Microsoft agreement and the separate Grounding with Bing terms of use, which exclude it from the Microsoft Data Protection AddendumProprietary service under the Kagi API Terms of Service. The MCP server is MIT and the OpenAPI file states Apache-2.0
Tools exposed3none
Read-only variant documentednono
llms.txtnono
Last release2026-11-022026-08-21
Terms last updated2025-11-012026-09-22
Privacy policy last updated2026-09-01no date given
Customer content may train modelsyesnot found in the text
Terms restrict automated accessyesyes
Terms restrict benchmarkingnot found in the textyes
Terms or service can change without noticenot found in the textnot found in the text
Arbitration or class-action waivernot found in the textnot found in the text
Popularitynone535 stars

How the scores have moved

Verdicts

Grounding with Bing Search

First-party Bing grounding inside Foundry Agent Service, called with Entra ID so the agent never holds a search key, at a published $14 per 1,000 transactions. The tools return a model's answer with citations, never the raw results, and data sent to them falls outside Microsoft's Data Protection Addendum and Azure's compliance boundary.

Kagi Search API

A public OpenAPI file, typed filters and API keys that can be limited by product and IP address make the API simple to call, at $12 per 1,000 searches. It is still a public preview, with no published rate limits and no free allowance, and the terms forbid storing results. Its status page logged only regional incidents since August.

Before you call either

Grounding with Bing Search

  1. Use the citations in the response annotations as the sources; the tool output itself is not returned, and the terms require showing the URLs and the Bing query link
  2. Expect each run to bill one transaction per tool call at $14 per 1,000, plus model tokens, and set count and freshness in the tool configuration
  3. Treat cited page text as untrusted input and don't put secrets or personal data in prompts, since queries leave the Azure compliance boundary
  4. On 429 back off exponentially; no Retry-After header is documented for the tool

Kagi Search API

  1. Send POST https://kagi.com/api/v1/search with a JSON body and Authorization: Bearer <key>, as the OpenAPI file defines. Only query is required
  2. Set limit to cap results returned. In the mixed search workflow the MCP tool applies the cap to each result category separately
  3. Use extract.count (1 to 10) only when page text is needed. Extraction is billed at the Extract rate on top of the search
  4. Do not store results. The API terms allow only the transient caching an application needs, and require deletion on termination
  5. On 429 back off before retrying. The response covers both rate limiting and an exhausted usage limit, and no Retry-After header is documented. Check status.kagi.com for regional incidents

Questions

Which is better for AI agents, Grounding with Bing Search or Kagi Search API?

Grounding with Bing Search scores 63.7 (B) on agent readiness against Kagi Search API's 56.1 (C), and leads in 3 of 7 scored categories. Kagi Search API leads on agent ergonomics and transparency & trust.

Which is cheaper for web search, Grounding with Bing Search or Kagi Search API?

Kagi Search API, at $12 per 1,000 requests against $14 per 1,000 requests for Grounding with Bing Search. These are the vendors' published prices for the job.

Do Grounding with Bing Search and Kagi Search API need an API key?

Grounding with Bing Search uses an OAuth sign-in. Kagi Search API needs an API key.

Can an agent call Grounding with Bing Search and Kagi Search API without installing anything?

Yes. Grounding with Bing Search has a hosted endpoint at https://{account}.services.ai.azure.com/api/projects/{project}/openai/v1/responses and Kagi Search API at https://kagi.com/api/v1/search.

Other comparisons with Grounding with Bing Search or Kagi Search API

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