# Flagsmith vs Harness Feature Management & Experimentation

> Harness Feature Management & Experimentation scores 69.2 (B) to Flagsmith's 61.2 (C) for feature flags. Prices, MCP, x402, uptime and agent notes side by side.

- Canonical: https://www.anchorterminal.com/compare/flagsmith-vs-harness-fme
- Markdown: https://www.anchorterminal.com/compare/flagsmith-vs-harness-fme.md (~4,700 tokens)
- Site index for agents: https://www.anchorterminal.com/llms.txt (the key docs and every listing in one file, at most 16 MB, about 4 million tokens: https://www.anchorterminal.com/llms-full.txt)
- API: https://www.anchorterminal.com/api/v1/index.json
- MCP: https://www.anchorterminal.com/mcp (the whole catalogue as tools, no key)
- DNS: dig +short TXT <slug>.grade.anchorterminal.com (the grade as a DNS TXT record, for a sandbox with no HTTP where names still resolve; also top., best.<category>. and <a>.vs.<b>. under the zone, and the same under grade.letme.dev)
- Licence: CC BY 4.0, credit Anchor Terminal and link this page (https://www.anchorterminal.com/terms/#data)
- Updated: 2026-11-07

Harness Feature Management & Experimentation scores 69.2 (B) on agent readiness against Flagsmith's 61.2 (C), and leads in 4 of 7 scored categories. Flagsmith leads on payments & pricing and transparency & trust. Both do feature flags.

- Flagsmith: grade C, 61.2/100, rank #620 of 1486. Markdown https://www.anchorterminal.com/tools/flagsmith.md · JSON https://www.anchorterminal.com/api/v1/tools/flagsmith.json
- Harness Feature Management & Experimentation: grade B, 69.2/100, rank #257 of 1486. Markdown https://www.anchorterminal.com/tools/harness-fme.md · JSON https://www.anchorterminal.com/api/v1/tools/harness-fme.json
- Best product analytics and experimentation tools for AI agents: https://www.anchorterminal.com/best/product-analytics/index.md
- All 153 product analytics comparisons: https://www.anchorterminal.com/compare/product-analytics/index.md

## Which one, for what

### Flagsmith (C)

Good for: Feature flags and experiments for teams that want open source or self-hosting, managed by an agent through MCP.

Ahead on:
- Payments & pricing, 40 against 15
- Transparency & trust, 77 against 61

Also in its favour:
- Open source

Watch for: The MCP docs call the server an early release, and experiment tools are marked beta

### Harness Feature Management & Experimentation (B)

Good for: Teams already on Harness, or Split customers, who want agents to inspect and change flags and segments with guard rails.

Ahead on:
- Reliability, 80 against 65
- Agent ergonomics, 83 against 55
- Security & auth, 79 against 65

Watch for: No FME prices are published; Enterprise is by quotation and free plan limits are unstated


## Why the edge

### Agent ergonomics: Harness Feature Management & Experimentation +28

- Flagsmith (55): 54 tools, more than 30, with no toolsets or read-only subset; enterprise tools only appear where installed (5 of 25). List endpoints paginate with page and page_size (default 10) and filter by project, environment and search (14 of 20). Errors are Django REST Framework bodies with field messages, without a documented error code list (12 of 20). Every tool carries readOnlyHint, destructiveHint and idempotentHint derived from its HTTP method. No idempotency keys for POST (14 of 20). Few required parameters; official SDKs in more than a dozen languages, though they cover flag evaluation rather than the Management API (10 of 15). 5+14+12+14+10 = 55.
- Harness Feature Management & Experimentation (83): 11 consolidated tools, and `--toolsets=fme` narrows the server to FME (25). Flag lists filter server-side by name, tag and rollout status, and the Admin API paginates with markerLimit (17 of 20). Documented status codes, 429 headers, and a harness_diagnose tool. Error bodies aren't documented per endpoint (14 of 20). harness_list and harness_get carry readOnlyHint, write tools ask for confirmation by elicitation, and harness_delete is marked destructive. No idempotency keys (15 of 20). Two required settings (API key, optional org and project, account ID read from the token); a Python Admin API wrapper and CLI, and SDKs in more than a dozen languages for evaluation (12 of 15). 25+17+14+15+12 = 83.

### Payments & pricing: Flagsmith +25

- Flagsmith (40): No x402, MPP or L402 (0). Plan prices and the per-million overage are public without login, though the page gives two overage rates for Start-Up ($50 per million and $7 per 100,000) (20). A $0 Free plan with 50,000 requests a month and a free BSD-3-Clause self-hosted edition. The pricing page doesn't say whether a card is needed, but the Free plan has no charge and the self-hosted edition needs no account (20). A person signs up in a browser, then approves OAuth or creates a key (0). 0+20+20+0 = 40.
- Harness Feature Management & Experimentation (15): No x402, MPP or L402 (0). No FME prices are published; harness.io/pricing lists FME only under Enterprise, priced by quotation (0). The docs describe a Start FME Free Plan step inside a Harness account; its limits and whether a card is needed aren't stated (15 of 20). A person signs up for Harness in a browser and creates a key or token (0). 0+0+15+0 = 15.

### Transparency & trust: Flagsmith +16

- Flagsmith (77): BSD-3-Clause for the core and the MCP server; the about page says most of the product is under that licence and some CI runs with private packages, so not every Cloud feature is in the open repository (25 of 30). The terms set Flagsmith as processor with 48-hour breach notice and EEA transfer rules, and the sub-processor list is dated 13 October 2025. The privacy policy dates from October 2023 and states no retention periods (16 of 30). The Gram-hosted MCP server was retired with a dated notice (30 June 2026), and three spec operations are marked deprecated, without a stated deprecation policy (10 of 20). The sub-processor list names providers and their countries (16 of 20). 25+16+10+16 = 67.
- Harness Feature Management & Experimentation (61): A closed service under Harness's subscription terms; the MCP server is MIT (18 of 30). The privacy statement covers website and sales data and defers customer data to the customer agreement and a published DPA; retention periods for customer data weren't found (18 of 30). A versioning policy for SDKs with support windows, and Split-era API endpoints marked deprecated with migration guides (14 of 20). Sub-processors are on the trust centre, which we didn't read, and the security page doesn't name data locations (10 of 20). 18+18+14+10 = 60.

### Reliability: Harness Feature Management & Experimentation +15

- Flagsmith (65): Graded on Flagsmith Cloud with the hosted lines. Statuspage at status.flagsmith.com with components for the Edge API, Admin API, dashboard and website (20). In the 90 days from 8 August, an Admin and SDK API outage on 28 October marked critical, posted at 21:56 UTC and resolved at 22:12 with no cause given, and a minor delay in processing flag changes on 10 September. The posted span of the outage is 16 minutes and its start isn't stated, so we read it as one serious incident under an hour (15 of 30). The Management API limit of 500 requests a minute is documented (15). No 429 handling, Retry-After or idempotency guidance was found in the docs (0). A public SLA commits to 99.95 per cent monthly uptime with service credits (10). The Management API is generally available, but the MCP docs call the server an early release, so half (5 of 10). 20+15+15+0+10+5 = 65.
- Harness Feature Management & Experimentation (80): Graded on the hosted FME Admin API with the hosted lines. Statuspage at status.harness.io with an FME component among 196 (20). In the 90 days from 8 August, two FME incidents: API write operations returned 499 errors for 30 minutes on 20 August (minor) and the FME user interface was unavailable for 15 minutes on 23 August (major, interface only; flag evaluation was unaffected per the post). No API outage of an hour or more (20 of 30). About 20 Admin API requests per 10 seconds per organisation and per IP, documented on the MCP page (15). 429 responses carry remaining and reset headers with guidance to wait for the larger reset, and the MCP server backs off and retries three times (15). No SLA was found on harness.io/pricing or the FME docs (0). FME is generally available and the MCP server is at 3.2.40 (10). 20+20+15+15+0+10 = 80.

### Security & auth: Harness Feature Management & Experimentation +14

- Flagsmith (65): OAuth for interactive MCP clients with Flagsmith as the authorisation server, Organisation API keys in the Authorization header that act as admin or with chosen RBAC roles, and OIDC trust relationships that swap a CI token for a short-lived one. Granular key roles need Scale-Up or Enterprise, so a Free key is all-powerful (25 of 30). RBAC roles can limit a key to reads, and change requests put a flag change through approval on Scale-Up and Enterprise. There is no read-only switch on the MCP server itself (14 of 20). No prompt-injection guidance; tools return names, descriptions and trait values written by people (3 of 15). Audit logs record every admin action and stream by webhook, on Scale-Up and Enterprise (11 of 15). The docs say Flagsmith has a SOC 2 Type 2 report available on request, the terms promise a yearly third-party penetration test, and SECURITY.md routes reports to support email. No security.txt, bug bounty or public advisory process was found (12 of 20). 25+14+3+11+12 = 65.
- Harness Feature Management & Experimentation (79): Admin API keys with combinable roles that can't be widened after creation, Harness PATs and SATs for central management, and Harness Platform OAuth on the hosted MCP endpoint. Credentials travel in headers (28 of 30). HARNESS_READ_ONLY removes every write, writes go through elicitation with a risk threshold for auto-approval, and FME change requests add approval for flag changes (19 of 20). No prompt-injection guidance; the tools return flag names, descriptions and rule data written by people (3 of 15). FME admin, environment and object audit logs, plus structured MCP audit events to file, webhook or OpenTelemetry sinks (13 of 15). SOC 1 and SOC 2 Type II, ISO 27001, 27017 and 27018, FedRAMP 20x, a security@harness.io disclosure route with a 24-hour response, a private bug bounty on request and annual external penetration tests. No security.txt (16 of 20). 28+19+3+13+16 = 79.

## Score by category

| Category | Weight | Flagsmith | Harness Feature Management & Experimentation | Edge |
| --- | --- | --- | --- | --- |
| Reliability | 16% (20 this run) | 65 | 80 | Harness Feature Management & Experimentation +15 |
| Performance | 10%, pending | pending | pending | not scored in this run |
| Schema & documentation | 13% (16.2 this run) | 67 | 71 | Harness Feature Management & Experimentation +4 |
| Agent ergonomics | 13% (16.2 this run) | 55 | 83 | Harness Feature Management & Experimentation +28 |
| Security & auth | 14% (17.5 this run) | 65 | 79 | Harness Feature Management & Experimentation +14 |
| Payments & pricing | 10% (12.5 this run) | 40 | 15 | Flagsmith +25 |
| Task success | 10%, pending | pending | pending | not scored in this run |
| Maintenance & community | 7% (8.8 this run) | 83 | 81 | Flagsmith +2 |
| Transparency & trust | 7% (8.8 this run) | 77 | 61 | Flagsmith +16 |
| Negative events | ≤15 | -2 | 0 | |
| **Total** | | **61.2 · C** | **69.2 · B** | |

## Facts side by side

| Fact | Flagsmith | Harness Feature Management & Experimentation |
| --- | --- | --- |
| Kind | HTTP API | HTTP API |
| Vendor | Bullet Train Ltd | Harness Inc. |
| Hosted endpoint | `https://mcp.flagsmith.com` | `https://mcp.harness.io/mcp` |
| Transports | HTTP, Streamable HTTP, stdio | HTTP, stdio, Streamable HTTP |
| Auth | OAuth or key | OAuth or key |
| Pricing | Freemium | Freemium |
| x402 | no | no |
| Licence | BSD-3-Clause | none |
| Tools exposed | 54 | 11 |
| Read-only variant documented | yes | no |
| llms.txt | no | yes |
| Last release | 2026-11-05 | 2026-11-04 |
| Terms last updated | 2026-09-01 | no date given |
| Privacy policy last updated | 2023-10-01 | no date given |
| Customer content may train models | not found in the text | not found in the text |
| Terms restrict automated access | not found in the text | not found in the text |
| Terms restrict benchmarking | not found in the text | yes |
| Terms or service can change without notice | not found in the text | not found in the text |
| Arbitration or class-action waiver | not found in the text | not found in the text |
| Popularity | 6.6k stars | 8.8k npm/wk |

## Verdicts

**Flagsmith.** Flagsmith pairs a BSD-licensed core with a hosted MCP server whose 54 tools come from its OpenAPI spec and carry read and destructive hints. A public 99.95 per cent SLA and SOC 2 report back the Cloud service. The MCP server is still an early release, and fine-grained key roles need a paid Scale-Up or Enterprise plan.

**Harness Feature Management & Experimentation.** Harness FME, formerly Split, gives agents 11 consolidated MCP tools with an FME-only toolset, a read-only switch and confirmation on writes, over an Admin API with documented limits and role-scoped keys. FME prices are not published, the free plan's limits are unstated, and the hosted MCP endpoint must be enabled by Harness Support.

## Before you call either

### Flagsmith

1. Send the key as `Authorization: Api-Key <key>`; the `Api-Key ` prefix is required and a bare key fails
2. Check whether the environment uses v2 feature versioning before choosing between segment-override and version-state tools
3. Use a key with a read-only RBAC role for analysis tasks, since a Free plan key has organisation admin rights
4. Pace Management API calls under 500 a minute; no Retry-After guidance is documented
5. Treat experiment results as possibly null until Flagsmith has computed them

### Harness Feature Management & Experimentation

1. Start the MCP server with `--toolsets=fme` so only FME resource types load
2. Call `harness_describe(resource_type='fme_feature_flag')` before a create or update to see the fields
3. Filter fme_feature_flag lists by name, tags or rollout status rather than listing every flag
4. Set HARNESS_READ_ONLY for analysis tasks; leave confirmation on for kill, restore and delete
5. On 429, wait at least the larger X-RateLimit-Reset-Seconds value before retrying

## Questions

### Which is better for AI agents, Flagsmith or Harness Feature Management & Experimentation?

Harness Feature Management & Experimentation scores 69.2 (B) on agent readiness against Flagsmith's 61.2 (C), and leads in 4 of 7 scored categories. Flagsmith leads on payments & pricing and transparency & trust.

### Do Flagsmith and Harness Feature Management & Experimentation need an API key?

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

### Can an agent call Flagsmith and Harness Feature Management & Experimentation without installing anything?

Yes. Flagsmith has a hosted endpoint at https://mcp.flagsmith.com and Harness Feature Management & Experimentation at https://mcp.harness.io/mcp.

### Are Flagsmith and Harness Feature Management & Experimentation open source?

Flagsmith is open source (BSD-3-Clause). No open-source release is listed for Harness Feature Management & Experimentation.


## For agents

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

## Other comparisons with Flagsmith or Harness Feature Management & Experimentation

- [Amplitude vs Flagsmith](https://www.anchorterminal.com/compare/amplitude-vs-flagsmith.md)
- [Amplitude vs Harness Feature Management & Experimentation](https://www.anchorterminal.com/compare/amplitude-vs-harness-fme.md)
- [Countly vs Flagsmith](https://www.anchorterminal.com/compare/countly-vs-flagsmith.md)
- [Countly vs Harness Feature Management & Experimentation](https://www.anchorterminal.com/compare/countly-vs-harness-fme.md)
- [Flagsmith vs GrowthBook](https://www.anchorterminal.com/compare/flagsmith-vs-growthbook.md)
- [Flagsmith vs LaunchDarkly](https://www.anchorterminal.com/compare/flagsmith-vs-launchdarkly.md)
- [Flagsmith vs Mixpanel](https://www.anchorterminal.com/compare/flagsmith-vs-mixpanel.md)
- [Flagsmith vs Optimizely Experimentation](https://www.anchorterminal.com/compare/flagsmith-vs-optimizely.md)
- [Flagsmith vs PostHog](https://www.anchorterminal.com/compare/flagsmith-vs-posthog.md)
- [Flagsmith vs Statsig](https://www.anchorterminal.com/compare/flagsmith-vs-statsig.md)
- [Harness Feature Management & Experimentation vs LaunchDarkly](https://www.anchorterminal.com/compare/harness-fme-vs-launchdarkly.md)
- [Harness Feature Management & Experimentation vs Mixpanel](https://www.anchorterminal.com/compare/harness-fme-vs-mixpanel.md)
- [Harness Feature Management & Experimentation vs Optimizely Experimentation](https://www.anchorterminal.com/compare/harness-fme-vs-optimizely.md)
- [Harness Feature Management & Experimentation vs PostHog](https://www.anchorterminal.com/compare/harness-fme-vs-posthog.md)
- [Harness Feature Management & Experimentation vs Statsig](https://www.anchorterminal.com/compare/harness-fme-vs-statsig.md)
- [Flagsmith vs Fullstory](https://www.anchorterminal.com/compare/flagsmith-vs-fullstory.md)
- [Flagsmith vs Heap](https://www.anchorterminal.com/compare/flagsmith-vs-heap.md)
- [Flagsmith vs OpenPanel](https://www.anchorterminal.com/compare/flagsmith-vs-openpanel.md)
- [Flagsmith vs Woopra](https://www.anchorterminal.com/compare/flagsmith-vs-woopra.md)
- [Fullstory vs Harness Feature Management & Experimentation](https://www.anchorterminal.com/compare/fullstory-vs-harness-fme.md)
- [Harness Feature Management & Experimentation vs Heap](https://www.anchorterminal.com/compare/harness-fme-vs-heap.md)
- [Harness Feature Management & Experimentation vs OpenPanel](https://www.anchorterminal.com/compare/harness-fme-vs-openpanel.md)
- [Harness Feature Management & Experimentation vs Woopra](https://www.anchorterminal.com/compare/harness-fme-vs-woopra.md)
- [Flagsmith vs Matomo](https://www.anchorterminal.com/compare/flagsmith-vs-matomo.md)
- [Flagsmith vs Mostly Good Metrics](https://www.anchorterminal.com/compare/flagsmith-vs-mostly-good-metrics.md)
- [GrowthBook vs Harness Feature Management & Experimentation](https://www.anchorterminal.com/compare/growthbook-vs-harness-fme.md)
- [Harness Feature Management & Experimentation vs Matomo](https://www.anchorterminal.com/compare/harness-fme-vs-matomo.md)
- [Harness Feature Management & Experimentation vs Mostly Good Metrics](https://www.anchorterminal.com/compare/harness-fme-vs-mostly-good-metrics.md)

---

Query this catalogue directly over MCP: https://www.anchorterminal.com/mcp (Streamable HTTP, no key). How: https://www.anchorterminal.com/agents/#mcp