Kernel vs Steel

Kernel 81

Scoped API keys with resource and action policies, project scoping and expiry, and OAuth 2.1 for MCP with project-limited tokens (30). Least privilege through scoped keys, a payment cap for cards through the MCP server and vault writes that need their own action (16). Pages an agent browses are untrusted, and we found no prompt-injection guidance in the docs read (4). Audit log search and export on Start-Up and above (13). SOC 2 Type II, HIPAA, PCI DSS and ISO 27001 on the security page and a HackerOne bounty (18). 30 + 16 + 4 + 13 + 18 = 81, before the deduction for the November 2026 incident.

Steel 56

Named API keys, shown once, revoked by deletion, with last-used times and a rotation guide. A global key covers the organisation and can create keys bound to one project through POST /v1/api-keys. No per-permission scopes were found (22). The documented CDP connection passes the key as apiKey in the wss://connect.steel.dev URL, a secret in a query string (minus 10). No read-only key. Projects isolate sessions, credentials and profiles, stored credentials are typed into pages without being shown to the agent, browser action endpoints reject localhost and private addresses since changelog 038, and the MCP server has a scrape-only profile and hands the browser to a person before logins and payments (13). The MCP server fences page content as untrusted and strips hidden text, and its README warns about injection. The API docs carry no such guidance (10). Session logs, recordings, Agent Traces, per-session cost and exports to JSON or CSV give the operator a per-call trail (13). A Vanta trust centre whose contents did not render for us, a HIPAA-ready BAA and SSO on Scale, and a disclosure policy with response times for the MCP server. No security.txt, bug bounty or certification report was found (8).

Kernel 53

Hosted reading. status.kernel.sh on incident.io with a public incident feed (20). In the 90 days from 8 August it lists browser connection failures on 10 September (54 minutes, major), frozen popups on 1 October (71 minutes, major), elevated API errors on 19 October (4 minutes, critical), proxy failures on 23 October (65 minutes, major) and browser creation errors on 4 November (29 minutes, major), plus minor ones. Several majors, two of them an hour or more (0). Rate limits are per organisation with headers on every response, and concurrency is published per plan, but the create-rate numbers aren't (8). 429 with Retry-After, SDK retries with a typed error, safe retry with the same MPP credential and 409 on concurrent pool changes (15). The terms mention service levels in an order form but no public SLA was found (0). The API and MCP server carry no beta label (10). 20 + 0 + 8 + 15 + 0 + 10 = 53.

Steel 63

Graded as a hosted service, on Steel Cloud. status.steel.dev runs on Better Stack with Steel API, Dashboard, Proxies and Connections components and 90 days of history, per the 8 October check (20). On 1 November its robots.txt disallows every path, so the history wasn't re-read. Per the 8 October check, the 4 hour 10 minute outage of 22 July 2026 has now left the 90-day window, leaving two majors in it, 5 hours 41 minutes of capacity errors on session creation on 23 August and 1 hour 55 minutes of failing session creation on 1 October. Two majors give 5, and anything posted after 8 October is unread, which would also score 5 as no readable history (5). Limits are published per plan, 60 and 600 requests a minute and 10 and 100 concurrent sessions, re-read on 1 November, and 20 a minute on Browser Tools (15). Browser Tools document 429 and a 503 marked safe to retry, the Agent Traces API says to wait for Retry-After, and the SDKs retry 408, 409, 429 and 5xx twice with backoff. No idempotency keys, though session creation accepts a caller-chosen sessionId (10). Support and uptime SLAs are listed for Enterprise only on the pricing page re-read on 1 November, with no terms published (3). The sessions API is not marked beta (10).

Kernel 65

MPP on POST /mpp/browsers, a 402 challenge paid with a Stripe shared payment token through Link, covering one browser product only, not the API or MCP server (20). Per-second prices public without a login (20). The Developer plan is free with $5 of monthly credit, but whether signup needs a card wasn't stated on the pages read (10). Through MPP an agent gets a browser with no account or key, though a person approves each Link payment (15). 20 + 20 + 10 + 15 = 65.

Steel 75

x402 version 2 at x402.steel.dev for scrape, screenshot and PDF, in USDC on Base or Solana. An unpaid request on 1 November 2026 again returned 402 asking 10000 base units, with the resource named as api.paysponge.com. Browser sessions, the main product, aren't covered, so partial (20). Per-hour, per-GB and per-1,000-call prices published without login, on a pricing page last edited 23 October 2026 with the same rates (20). Launch plan with $30 of one-time credit valid 90 days, and the quickstart says no card is required (20). An agent with a wallet gets a scrape, screenshot or PDF with no account, but a browser session needs a person to sign up or run the Stripe CLI, so we award 15 of 20.

Kernel 90

The changelog's latest entry is 16 October 2026 and the MCP server repository has commits on 6 November (30). More than three dated changes in 90 days, scoped keys, memory tiers, GPU tier and card payments among them (20). A closed service with a public changelog, Discord, email support and an open-source MCP server with 210 commits since 8 August (15). Official SDKs in three languages, and the MCP server in the registry as com.onkernel/kernel-mcp-server 1.1.0 (15). CI and tests in the MCP repository (10). 30 + 20 + 15 + 15 + 10 = 90.

Steel 82

steel-browser v0.5.5-beta was tagged on 31 October 2026 and changelog 038 is dated 2 October (30). In the 90 days from 3 August, changelog entries on 18 and 25 September and 2 October, steel-browser v0.5.4-beta (25 August) and v0.5.5-beta (31 October), and the MCP server's 3.0.0 on main (9 September). The 24 July entry has left the window and no changelog entry has followed 038 (20). Public changelog, Discord and email support, and steel-browser merged 32 commits between v0.5.4-beta and v0.5.5-beta, among them fixes for session-ID validation in casting, file:// blocking and a Node CVE. GitHub issue reply times were not read (15). Official SDKs exist, but the newest tags are steel-node v0.20.0 and steel-python v0.19.0 from 23 June, with no commit after 11 September, npm and PyPI didn't resolve from our shell on 1 November, and the MCP server is not in the MCP registry, per the 8 October check (9). CI workflows in steel-browser and a test, byte-budget and conformance suite in the MCP server. Whether they pass was not read (8).

Kernel 93

OpenAPI at kernel.sh/openapi.json and per-endpoint Markdown reference (25). llms.txt with 423 entries and a Markdown twin for each page (10). Endpoint descriptions say when to use alternatives ("For interactive browsing, use GET /audit-logs", pools for bursty traffic) (17). Typed parameters with enums and limits such as memory sizes and timeout maximums (13). Code samples in TypeScript, Python and Go, and documented status codes such as 409 and 204 on pool acquire (13). A dated public changelog and SDK changelogs (15). 25 + 10 + 17 + 13 + 13 + 15 = 93.

Steel 86

OpenAPI 3.0.3 at docs.steel.dev/openapi.json with 51 paths and 75 operations and the steel-api-key header scheme (25). llms.txt, llms-full.txt and a Markdown twin of every docs page (10). 65 of 75 operations carry a description, and the MCP server's tool descriptions say when to use each tool and when to pick another (16). Inputs are typed with enums, UUID formats and list limits of 1 to 100, but timeout and concurrency carry no real bounds and useProxy and region have no stated type (11). One shared error schema is attached to most operations and the docs have error tables for Browser Tools and Agent Traces. The spec holds one example, and 429 is declared on session creation only (11). Paths are versioned under /v1 and the changelog is public and numbered, with dates in page metadata. The spec's own version reads 0.0.1 (13).

Kernel 84

Graded mainly on the API, with the MCP server noted. Responses are scoped per resource and the MCP server groups actions into about 32 tools (18). List endpoints page with limit and offset and filter by status (18). Typed SDK errors and documented 409 on concurrent changes, 204 on a pool timeout and 429 (17). Retrying an MPP purchase with the same credential returns the same browser, and the MCP tools carry readOnlyHint where read-only (16). SDKs in TypeScript, Python and Go plus a CLI, with defaults such as a 60-second timeout (15). 18 + 18 + 17 + 16 + 15 = 84.

Steel 79

Scrape returns only the formats asked for (HTML, cleaned HTML, Markdown or readability text), lists take limit, and the MCP server holds its 16 tool definitions to a 17,000 byte budget checked in CI, with a three-tool scrape profile (20). Sessions list by cursor with a status filter and a default page of 50, other lists take limit and offset, and traces filter by time and event type (17). Errors return message, linkToDocs and validation context, with documented 401 messages. No stable machine-readable error codes were found (15). No idempotency keys. A caller-chosen sessionId, inactivityTimeout and release-all help with retries and clean-up, and every MCP tool carries read-only, destructive or idempotent annotations (12). Session creation needs no parameters, and there are SDKs for Node and Python, with Rust and Go per Steel's blog (15).