Comparison — vendor pages read 2026-11-11
Observability Unified vs PostHog
PostHog is a cloud-first product platform: product analytics, session replay, logs, AI Observability, and distributed tracing in beta since July 2026.
Observability Unified is a self-hosted platform that connects traces, logs, replay, profiles, and AI agent activity through shared IDs, and gives AI agents evidence with citations through MCP. Each row below says Yes, Partial, or No for both products and links to the page that supports it.
Where Observability Unified differs
- MCP write tools off unless enabled. Writes register only with OBS_MCP_ENABLE_WRITES=true
- MCP results link to source records. Evidence bundles with citations; dashboard deep links when OBS_DASHBOARD_URL is set
- Agent tool calls alongside app traces. Agent Action Graph links tool calls to traces
- Records what an agent's tool call changed. Before, after, and diff values your app attaches to a tool call, stored as sent
- Compare releases and flag variants. Error-rate lift per version and flag variant, normalized for traffic share
- Shared-dependency contention vs code regression. Shared-degradation verdicts separate contention from the new version
- Root cause states its level of proof. Proof tier from unverified locus to counterfactual verified, kept apart from link certainty
- Fix verified by re-running the failing case. Same eval input fails on the baseline and passes on the candidate
- Remediation behind approval or a policy gate. Approval queue or single-use grant; your runner executes; a watchdog checks recovery
- Distributed tracing (OTLP). OTLP over HTTP; front gRPC with a Collector
- Browser click linked to its backend trace. x-obs-interaction links a click to its trace, logs, and replay (browser SDK or header)
- CPU profile from a trace. When profiling is enabled and samples carry the trace ID
- Points out gaps in your instrumentation. Flags spans with unexplained self-time in the waterfall and in get_trace
- Run the full platform yourself. Docker image, Node + Postgres/S3, or Cloudflare
Where PostHog offers more
- Write your own queries over telemetry. SQL (HogQL, ClickHouse-based) over events including AI traces
- Vendor-hosted cloud service. PostHog Cloud
- Built-in single sign-on. SAML and OIDC on the Scale package and up
Capability by capability
Investigating with AI agents
| Capability | Observability Unified | PostHog |
|---|---|---|
| First-party MCP server | Yes Local stdio server, @obsunified/mcp-server our docs | Yes Hosted endpoint posthog.com |
| MCP write tools off unless enabled | Yes Writes register only with OBS_MCP_ENABLE_WRITES=true our docs | Partial Read and write by default; read-only mode is opt-in posthog.com |
| MCP results link to source records | Yes Evidence bundles with citations; dashboard deep links when OBS_DASHBOARD_URL is set our docs | Partial Some tools return PostHog links posthog.com |
| Agent tool calls alongside app traces | Yes Agent Action Graph links tool calls to traces our docs | Partial Correlate by trace ID in SQL; not linked in the UI posthog.com |
| Compacted evidence for AI agents | Yes CCR bundles collapse repeated logs to exemplars within a token budget; refs expand them our docs | Yes MCP log patterns collapse logs into up to 200 templates that pivot to raw lines posthog.com |
| Agent skills for coding agents | Yes Instrument and investigate skills, released as .skill bundles our docs | Yes Official PostHog AI plugin ships skills for Claude Code, Cursor, Codex github.com |
Observing your own AI agents
| Capability | Observability Unified | PostHog |
|---|---|---|
| Records what an agent's tool call changed | Yes Before, after, and diff values your app attaches to a tool call, stored as sent our docs | Partial Tool and function spans capture input and output state posthog.com |
| MCP calls recorded with trace context | Yes MCP spans join the action graph; an optional allow-listed envelope records the context our docs | Yes MCP Analytics (beta) records MCP tool calls per agent session posthog.com |
| Production traces become eval cases | Yes Save as eval case from a trace or run; candidate runs compared step by step (HTTP API) our docs | Yes Add traces to datasets (beta) and compare runs in offline evals posthog.com |
Change-aware investigation and remediation
| Capability | Observability Unified | PostHog |
|---|---|---|
| Compare releases and flag variants | Yes Error-rate lift per version and flag variant, normalized for traffic share our docs | Partial Filter issues by release and insights by flag posthog.com |
| Shared-dependency contention vs code regression | Yes Shared-degradation verdicts separate contention from the new version our docs | Partial Trace waterfall across services posthog.com |
| Root cause states its level of proof | Yes Proof tier from unverified locus to counterfactual verified, kept apart from link certainty our docs | Partial Inbox agent researches root cause posthog.com |
| Fix verified by re-running the failing case | Yes Same eval input fails on the baseline and passes on the candidate our docs | Partial Agent PRs add a regression test; a scout re-checks posthog.com |
| Remediation behind approval or a policy gate | Yes Approval queue or single-use grant; your runner executes; a watchdog checks recovery our docs | Partial Agent PRs are reviewed; flag changes need approval posthog.com |
| Matches new incidents to past ones | Yes Prior findings matched by fingerprint appear in incident evidence bundles our docs | Yes Self-driving scouts keep memory of past findings and dedupe against them posthog.com |
Signals
| Capability | Observability Unified | PostHog |
|---|---|---|
| Distributed tracing (OTLP) | Yes OTLP over HTTP; front gRPC with a Collector our docs | Partial OTLP distributed tracing in beta (July 2026) posthog.com |
| Structured logs | Yes Trace-correlated our docs | Yes OTLP-native, GA January 2026 posthog.com |
| AI / LLM observability | Yes AI calls, agent runs, evals our docs | Yes AI Observability posthog.com |
| Session replay | Yes rrweb, browser DOM only our docs | Yes rrweb-based posthog.com |
| Browser click linked to its backend trace | Yes x-obs-interaction links a click to its trace, logs, and replay (browser SDK or header) our docs | Partial Backend spans carry the replay session ID posthog.com |
| CPU profile from a trace | Yes When profiling is enabled and samples carry the trace ID our docs | Not marketed† No CPU profiling product in the sitemap posthog.com |
| One ID chain from user to agent action | Yes user_id → session_id → interaction_id → trace_id → span_id → action_id our docs | Yes Session, person, backend spans and LLM events share IDs (tracing beta) posthog.com |
| Write your own queries over telemetry | Partial Search and filters; no query language or SQL editor our docs | Yes SQL (HogQL, ClickHouse-based) over events including AI traces posthog.com |
| Points out gaps in your instrumentation | Yes Flags spans with unexplained self-time in the waterfall and in get_trace our docs | Partial Agent skill reads span self-time as uninstrumented gaps; ingestion warnings github.com |
Deployment and access
| Capability | Observability Unified | PostHog |
|---|---|---|
| Run the full platform yourself | Yes Docker image, Node + Postgres/S3, or Cloudflare our docs | Partial Docker Compose self-host, officially unsupported posthog.com |
| Vendor-hosted cloud service | No Self-hosted only our docs | Yes PostHog Cloud posthog.com |
| Built-in single sign-on | No Front it with Cloudflare Access or oauth2-proxy our docs | Yes SAML and OIDC on the Scale package and up posthog.com |
Choosing between them
Choose PostHog if product analytics comes first and you want session replay, logs, and tracing alongside it.
Choose Observability Unified if you want AI agents and engineers to investigate the same production evidence, with the telemetry kept on infrastructure you run. It is early-stage software suited to single-team deployments; the documented trade-offs include no built-in SSO, OTLP over HTTP only, and browser-only session replay.
How these cells were checked
Yes and Partial cells cite the vendor's own docs, pricing, product page, or official repository. No is used only where the cited page says so. Not marketed† means we read the vendor's product pages and found no such capability; it is an inference, not a vendor statement. Not stated means the vendor's docs do not say either way.
Rows for MCP write defaults, MCP links, agent tool calls, CPU profiles, self-hosting, and SSO were read on 2026-11-10 (ledger with excerpts). Rows for release and flag comparison, proof of cause, fix verification, gated remediation, click to trace, and dependency contention were read on 2026-11-11 (ledger with excerpts). Rows for compacted evidence for agents, agent skills, one ID chain, and instrumentation gaps were read on 2026-11-11 (ledger with excerpts). Rows for tool-call side effects, MCP call recording, production traces to eval cases, incident memory, and ad-hoc queries were read on 2026-11-11 (ledger with excerpts). The MCP server row was read on 2026-11-10 (ledger), and the remaining rows on 2026-10-13 (ledger). Vendors change their products often; if a cell is out of date, send a correction. The full comparison covers all nine vendors with excerpts.