Moduna vs Spanlens

Moduna and Spanlens are both inference engines & infra tracked by AIDiveForge. Below is a side-by-side comparison of pricing, capabilities, platforms, and ownership — sourced from each tool's live website and verified before publishing.

Moduna

Moduna instruments your existing agent stack with a single SDK call, then clusters the conversations already flowing through production into intent groups, failure patterns, and demand signals your roadmap doesn't yet reflect. The intent dashboard ranks blind spots by non-resolution rate and frustration trend — not by gut feel. A 42% failure rate on refund escalations, surfaced and ranked, is a different conversation than a hunch that 'users seem unhappy with billing.' Where it breaks: Moduna analyzes; it does not fix. The structured evidence it surfaces still requires a product decision and an engineering sprint to act on.

Spanlens

Spanlens sits in front of your LLM provider via a single baseURL change, recording every call's cost, latency, tokens, and full request-response body with no SDK rewrite required. Agent runs surface as waterfall span trees so you can identify the one step consuming 80% of wall-clock time. The model recommender flags GPT-4o calls that look like classification tasks and shows the cost delta if you swap — with numbers from your own traffic, not benchmarks. The eval and experiment layer lets you replay a fixed dataset across prompt versions before you ship, so quality regressions don't surprise you in production. PII scanning and anomaly detection run at log time, which matters when sensitive data crosses the wire at 3 a.m. with nobody watching.

Attribute	Moduna	Spanlens
Pricing	Paid	Paid
Price	—	$29/mo
Free trial	No	No
Open source	No	Yes
Has API	Yes	Yes
Self-hosted option	No	Yes
Platforms	Web SaaS	Node.js, Python, Next.js, Edge, self-hosted
Pros	Single-integration instrumentation against an existing agent stack, which means you don't rebuild your observability layer — you add one SDK call and the conversation data you're already generating becomes structured product evidence. Intent clustering ranked by failure rate and frustration trend, so product teams arrive at roadmap reviews with ranked, conversation-backed priorities rather than competing anecdotes from support and sales. Blind-spot detection that flags confident-but-unhelpful agent responses — the failure mode that trace logs mark as successful — so you find the 42%-failure refund flow before users churn over it rather than after. High-value conversation routing signals, such as enterprise pricing inquiries hitting the agent, so sales and product teams can identify handoff gaps that are costing revenue rather than just degrading experience. Continuous production signal rather than periodic surveys, which means demand shifts surface in the dashboard as they accumulate — you're not waiting for a quarterly NPS cycle to learn the subscription cancellation flow is broken.	Proxy-layer instrumentation via a single baseURL change, so existing code requires no structural rewrite and every provider call is captured from day one rather than after a manual instrumentation sprint. Per-user and per-route cost attribution, which means you can identify the specific customer or endpoint burning disproportionate budget before it compounds across a billing cycle. Agent waterfall trace trees with critical-path highlighting, so a slow or expensive step in a multi-agent run is pinpointed in seconds instead of reproduced manually in a staging environment. Experiment runner replays a fixed dataset across prompt versions and models with quality, cost, and latency compared side by side, which means you ship with evidence that v8 is better than v7 rather than finding out the hard way in production. Self-hosted deployment via Docker Compose under MIT license, so teams with data residency or audit requirements can run the full platform without sending trace data to a third-party cloud.
Cons	Moduna surfaces what to fix but ships nothing — every ranked blind spot still requires a product decision, a sprint, and a deployment before users see improvement. Teams expecting the tool to close the loop on agent failures will be writing tickets manually from the dashboard. No self-hosted option exists, meaning every production conversation passes through Moduna's infrastructure. Teams operating under strict data residency or contractual restrictions on third-party data processors hit this wall immediately and have no workaround short of not using the product. LangChain is the only framework named explicitly in the vendor's integration documentation. Teams running other agent frameworks — or proprietary orchestration layers — face an unverified integration path. If the SDK doesn't support their stack, the single-integration promise requires custom instrumentation work before any insight flows. The tool's value concentrates in post-hoc analysis of accumulated conversation volume. Teams running low-traffic agents, internal tools, or early-stage deployments with thin conversation data will see sparse intent clusters and statistically thin failure rates — at which point the ranked opportunity output is noise, not signal, and teams revert to manual conversation review.	PII detection is regex-based and runs at log time as a flag — not a pre-storage redaction guarantee. Teams operating under HIPAA or SOC 2 controls where sensitive data must never reach a log store, even briefly, need a dedicated redaction layer upstream of Spanlens or a different architecture entirely. The LLM-as-judge eval scoring is a single 0–1 scalar per response. Teams needing structured, multi-criteria evaluation rubrics — for example, factual accuracy scored separately from tone and policy compliance — hit the ceiling of what the built-in scorer expresses and end up maintaining a custom eval harness alongside Spanlens. At high request volumes where the proxy layer adds measurable latency to every call, teams running latency-sensitive production paths at scale have moved to SDK-side instrumentation tools or full APM platforms with LLM plugins, where the observability path is out of band rather than in the critical path.

Bottom line

Spanlens is open source. Choose based on which difference matters most for your workflow.

Frequently asked questions

What is the difference between Moduna and Spanlens?

Moduna is Paid, while Spanlens is Paid and open source. Compare pricing, free trial, API, platforms, and pros/cons in the table above on AIDiveForge.

Is Moduna better than Spanlens?

It depends on your workflow. Use the side-by-side attributes (pricing, open source, API, self-hosted, platforms) to decide. AIDiveForge does not rank a universal winner — we publish verified facts so you can choose.