FIXSIM

FIXSIM provides a FIX Protocol testing platform offering sandbox environments, certification tools, and live FIX message simulation. It enables OMS/EMS vendors and broker‑dealers to validate session logic, replay messages, and automate regression testing without installations or sales calls. The service includes free trials, pricing details, tutorials, and extensive resources for FIX protocol developers.

FIXSIM publishes 10 API contracts indexed on the APIs.io network, including Executions In API, Executions Out API, Instances API, and 7 more. Tagged areas include FIX, FIX Protocol, Testing, Sandbox, and Financial Services.

The FIXSIM catalog on APIs.io includes 1 JSON-LD context and 1 Spectral governance ruleset.

FIXSIM’s developer surface includes changelog, sandbox, pricing, getting-started guide, API reference, authentication, and 17 more developer resources.

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44.2/100 developing Agent 19/100 agent aware Full breakdown ↓
scored 2026-11-13 · rubric v0.28.0 · Show this score on your site →

AccessPaid

1 published contract

FIX FIX Protocol Testing Sandbox Financial Services

Kin Score

Kin Score How this is scored →
scored 2026-11-13 · rubric v0.28.0

Composite quality — 44.2/100 · developing

Contract Quality 10.9 / 21

Developer Ergonomics 8.1 / 17

Access Clarity 8.7 / 17

Operational Transparency 1.6 / 11

Contract Governance 2.2 / 10

Discoverability 5.6 / 9

Regulatory Posture 2.8 / 15

Agent readiness — 19/100 · agent aware

Machine-Readable Contract 18 / 18

Agentic Access Contract 10 / 10

Documented Reversibility 0 / 6

MCP Server 0 / 12

Machine-Readable Auth 10 / 10

Idempotency 0 / 9

Stable Error Semantics 8 / 8

Request/Response Examples 0 / 7

Rate-Limit Signaling 0 / 7

Typed Event Surface 0 / 6

Agent Skills 0 / 5

Well-Known Catalog 0 / 4

Consent & Bot Identity 0 / 3

A2A Agent Card 0 / 8

Dry-Run / Simulate Mode 0 / 4

Delegated User Identity 0 / 6

Protected Resource Metadata 0 / 5

Registration Without a Human 0 / 6

Agentic Commerce Well-Known Document 0 / 5

Pagination 0 / 5

Distinct Operations 3 / 3

MCP Tool Quality 6 / 6

Regulatory Posture applies to this provider. Its tags matched the Horizontal (data, software, accessibility, platform) regime, so Regulatory Posture carries 15 points of the composite. If this regime is wrong for your business, say so on your provider repo — the applicability map is public and we will correct it.

Create-or-Update Ergonomics could not be measured. We hold no machine-readable contract for this provider to read, so there is nothing to measure a write surface against. Excluded rather than scored zero: never-measured and measured-empty are different facts. Publishing an OpenAPI is what makes this facet — and several others — scorable at all.

The six quality facets above are damped to 85 points between them, because the conditional facet above carries the other 15. That is why each facet's contribution is shown against a damped maximum: raising a quality facet moves the composite by 85% of its nominal weight, not 100%. The full arithmetic is at apis.io/rating/.

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Agent readiness — checks not met, largest first (exact, from this profile):

MCP Server +12 pts — deployment.mode + probe verdict on the mcp/ manifest, not the pointer; an unprobed slug falls back to authorship Ask about this →
Idempotency +9 pts — OpenAPI mutating operations declare an idempotency key — a header, a request-body property, or a named de-duplication token whose own description says so (verified); else common[].type matches /idempoten/i (documented) Ask about this →
A2A Agent Card +8 pts — a2a/-a2a.yml manifest, graded on conformance.grade against A2A 1.0.0 Ask about this →
Rate-Limit Signaling +7 pts — OpenAPI responses document X-RateLimit-* / RateLimit headers (verified), else a rate_limits artifact or RateLimits link (documented) Ask about this →
Request/Response Examples +7 pts — share of operations carrying request/response examples; else an Examples / Code Samples link Ask about this →
Registration Without a Human +6 pts — a `registration_endpoint` in the served RFC 8414 / OIDC discovery document Ask about this →

10 more unmet checks in the Agent Readiness table above.

Kin Score — facets with the most composite points still available (weight × headroom):

Contract Quality scores 51.5 — up to +12.1 composite points Ask about this →
Operational Transparency scores 14.3 — up to +11.1 composite points Ask about this →
Developer Ergonomics scores 47.6 — up to +10.5 composite points Ask about this →

Each check links to what satisfies it. Publish the artifact, or tell us where it already lives, and the score moves on the next scoring run.

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Improve this rating by publishing the missing artifacts — every area above can be raised, and the full rubric is at apis.io/rating/. Every facet and dimension name above is a link: it opens that measurement's own page — what it means, the exact checks that feed it, how the whole catalog distributes on it, and the providers at the top of it. This rating is computed from the provider profile at artifacts.apis.io/fixsim-com/apis.yml: open an issue on github.com/api-evangelist/fixsim-com to ask a question or point us at an artifact you publish. Submit an artifact on GitHub — free → Manage your own listing — the Influence plan, $499/mo →

Standards implemented 1

Standards this provider implements or carries. De facto ones are profiled and measured by the API Commons; formal ones come from the standards directory and are linked by the provider's own tags. The evidence column says how each claim was established — not that it was made.

OpenAPI

measured — observed by APIs.io (published)

APIs 10

Individual APIs this provider publishes, each with its own machine-readable definition.

FIXSIM Executions In API

The ExecutionsIn API from FIXSIM — 4 operation(s) for executionsin.

FIXSIM Executions Out API

The ExecutionsOut API from FIXSIM — 5 operation(s) for executionsout.

FIXSIM Instances API

The Instances API from FIXSIM — 1 operation(s) for instances.

FIXSIM Orders In API

The OrdersIn API from FIXSIM — 5 operation(s) for ordersin.

FIXSIM Orders Out API

The OrdersOut API from FIXSIM — 6 operation(s) for ordersout.

FIXSIM Raw Messages API

The RawMessages API from FIXSIM — 1 operation(s) for rawmessages.

FIXSIM Securities API

The Securities API from FIXSIM — 1 operation(s) for securities.

FIXSIM Sessions API

The Sessions API from FIXSIM — 3 operation(s) for sessions.

FIXSIM Session Settings API

The SessionSettings API from FIXSIM — 1 operation(s) for sessionsettings.

FIXSIM SSO API

The Sso API from FIXSIM — 4 operation(s) for sso.

Scroll for all 10

FIXSIM API pricing

Prices published by FIXSIM, read 2026-11-08 from www.fixsim.com/pricing.

Plan	Price
Starter	$500/ month
Pro	from $1,500/ month
Enterprise	Custom

Plan details, limits and sources →

Pricing Plans 1

Published pricing tiers and plan structures.

FIXSIM Plans Pricing

3 plans

PLANS

Semantic Vocabularies 1

JSON-LD contexts and semantic vocabularies used across these APIs.

Fixsim Com Context

22 classes · 97 properties

JSON-LD

Spectral Rules 1

Spectral governance rulesets for linting and validating these APIs. Counts are the severity each rule declares, not results of running them.

FIXSIM API Rules

33 rules · 29 error-severity 2 warn-severity 2 info-severity

SPECTRAL

JSON Schema 10

Standalone JSON Schema definitions for this provider's data models.

ExecutionsIn

25 properties

JSON SCHEMA

ExecutionsOut

26 properties

JSON SCHEMA

InstanceInfo

4 properties

JSON SCHEMA

NewSecurity

4 properties

JSON SCHEMA

OrderSingleIn

16 properties

JSON SCHEMA

OrderSingleOut

16 properties

JSON SCHEMA

RawMessage

1 properties

JSON SCHEMA

Security

5 properties

JSON SCHEMA

SessionInfo

15 properties

JSON SCHEMA

SessionSettings

19 properties

JSON SCHEMA

Scroll for all 10

Security Posture 2

Authentication, domain security, vulnerability disclosure, and trust-center signals.

FIXSIM Authentication

apiKey · 1 scheme

SECURITY

FIXSIM Domain Security

TLSv1.3 · HSTS · DMARC

SECURITY

Agentic Access (API Evangelist recommendations) 1

Recommended x-agentic-access execution contracts for AI agents.

FIXSIM Agentic Access

84 operations · 40 acting

AGENTIC

Resources

Get Started 4

Portal, sign-up, and the first successful call

Sandbox

Sandbox

DeveloperPortal

GettingStarted

Documentation 1

Reference material describing how the API behaves

APIReference

APIReference

Agent Surfaces 2

MCP servers, agent skills, and machine-readable catalogs

AgenticAccess

AgenticAccess

LLMsTxt

LLMsTxt

Design & Contract 6

Pagination, idempotency, versioning, errors, and events

Spectral

JSONLD

Vocabulary

DataModel

ErrorCatalog

Conformance

Access & Security 2

Authentication, authorization, and security posture

Authentication

Authentication

DomainSecurity

DomainSecurity

Operate 2

Status, limits, changes, and where to get help

ChangeLog

ChangeLog

ChangeLog

ChangeLog

Commercial 4

Pricing, plans, and the legal terms of use

Plans

TermsOfService

PrivacyPolicy

Pricing

Company 1

The organization behind the API

Website

Website

Other 1

Properties that don't map to a standard resource type

Hosts

Hosts

Source (apis.yml)

aid: fixsim-com
name: FIXSIM
accessModel:
  pricing: paid
  onboarding: unknown
  trial: false
  try_now: false
  public: false
  label: Paid
  confidence: high
  source:
  - plans
  - authentication
  - security
  - sandbox
  generated: '2026-11-13'
  method: derived
image: https://www.fixsim.com/assets/img/og-image.png
description: 'FIXSIM provides a FIX Protocol testing platform offering sandbox environments, certification tools, and live
  FIX message simulation. It enables OMS/EMS vendors and broker‑dealers to validate session logic, replay messages, and automate
  regression testing without installations or sales calls. The service includes free trials, pricing details, tutorials, and
  extensive resources for FIX protocol developers.

  '
url: https://artifacts.apis.io/fixsim-com/apis.yml
x-type: company
x-source: harvest:mcp-registry
x-tier: profiled
x-tier-reason: enrichment pass 2026-11-08 (modular-v1; was harvest)
specificationVersion: '0.20'
created: '2026-11-08'
modified: '2026-11-08'
tags:
- FIX
- FIX Protocol
- Testing
- Sandbox
- Financial Services
maintainers:
- FN: Kin Lane
  email: kin@apievangelist.com
- FN: APIs.json
  email: info@apis.io
common:
- type: AgenticAccess
  url: agentic-access/fixsim-com-agentic-access.yml
- type: Plans
  url: plans/fixsim-com-plans-pricing.yml
- type: Spectral
  url: rules/fixsim-com-rules.yml
- type: JSONLD
  url: json-ld/fixsim-com-context.jsonld
- type: Vocabulary
  url: vocabulary/fixsim-com-vocabulary.yml
- type: DataModel
  url: data-model/fixsim-com-data-model.yml
- type: ChangeLog
  url: changelog/fixsim-com-changelog.yml
- type: Sandbox
  url: sandbox/fixsim-com-sandbox.yml
- type: ErrorCatalog
  url: errors/fixsim-com-problem-types.yml
- type: Conformance
  url: conformance/fixsim-com-conformance.yml
- type: LLMsTxt
  url: llms/fixsim-com-llms.txt
- type: Hosts
  url: hosts/fixsim-com-hosts.yml
- type: TermsOfService
  url: https://www.fixsim.com/tos
- type: Sandbox
  url: https://www.fixsim.com/sandbox
- type: PrivacyPolicy
  url: https://www.fixsim.com/privacypolicy
- type: Pricing
  url: https://www.fixsim.com/pricing
- type: DeveloperPortal
  url: https://portal.fixsim.com
- type: ChangeLog
  url: https://www.fixsim.com/whats-new
- type: GettingStarted
  url: https://www.fixsim.com/fix-onboarding-delays
- type: APIReference
  url: https://portal.fixsim.com/swagger/index.html
- type: Authentication
  url: authentication/fixsim-com-authentication.yml
- type: DomainSecurity
  url: security/fixsim-com-domain-security.yml
- type: Website
  url: https://fixsim.com/
apis:
- aid: fixsim-com:fixsim-com-executionsin-api
  name: FIXSIM Executions In API
  description: The ExecutionsIn API from FIXSIM — 4 operation(s) for executionsin.
  humanURL: https://portal.fixsim.com/swagger/index.html
  baseURL: https://portal.fixsim.com
  tags:
  - ExecutionsIn
  properties:
  - type: OpenAPI
    url: openapi/fixsim-com-executionsin-api-openapi.yml
  - type: JSONSchema
    url: json-schema/fixsim-com-executions-in-schema.json
- aid: fixsim-com:fixsim-com-executionsout-api
  name: FIXSIM Executions Out API
  description: The ExecutionsOut API from FIXSIM — 5 operation(s) for executionsout.
  humanURL: https://portal.fixsim.com/swagger/index.html
  baseURL: https://portal.fixsim.com
  tags:
  - ExecutionsOut
  properties:
  - type: OpenAPI
    url: openapi/fixsim-com-executionsout-api-openapi.yml
  - type: JSONSchema
    url: json-schema/fixsim-com-executions-out-schema.json
- aid: fixsim-com:fixsim-com-instances-api
  name: FIXSIM Instances API
  description: The Instances API from FIXSIM — 1 operation(s) for instances.
  humanURL: https://portal.fixsim.com/swagger/index.html
  baseURL: https://portal.fixsim.com
  tags:
  - Instances
  properties:
  - type: OpenAPI
    url: openapi/fixsim-com-instances-api-openapi.yml
  - type: JSONSchema
    url: json-schema/fixsim-com-instance-info-schema.json
- aid: fixsim-com:fixsim-com-ordersin-api
  name: FIXSIM Orders In API
  description: The OrdersIn API from FIXSIM — 5 operation(s) for ordersin.
  humanURL: https://portal.fixsim.com/swagger/index.html
  baseURL: https://portal.fixsim.com
  tags:
  - OrdersIn
  properties:
  - type: OpenAPI
    url: openapi/fixsim-com-ordersin-api-openapi.yml
  - type: JSONSchema
    url: json-schema/fixsim-com-order-single-in-schema.json
- aid: fixsim-com:fixsim-com-ordersout-api
  name: FIXSIM Orders Out API
  description: The OrdersOut API from FIXSIM — 6 operation(s) for ordersout.
  humanURL: https://portal.fixsim.com/swagger/index.html
  baseURL: https://portal.fixsim.com
  tags:
  - OrdersOut
  properties:
  - type: OpenAPI
    url: openapi/fixsim-com-ordersout-api-openapi.yml
  - type: JSONSchema
    url: json-schema/fixsim-com-order-single-out-schema.json
- aid: fixsim-com:fixsim-com-rawmessages-api
  name: FIXSIM Raw Messages API
  description: The RawMessages API from FIXSIM — 1 operation(s) for rawmessages.
  humanURL: https://portal.fixsim.com/swagger/index.html
  baseURL: https://portal.fixsim.com
  tags:
  - RawMessages
  properties:
  - type: OpenAPI
    url: openapi/fixsim-com-rawmessages-api-openapi.yml
  - type: JSONSchema
    url: json-schema/fixsim-com-raw-message-schema.json
- aid: fixsim-com:fixsim-com-securities-api
  name: FIXSIM Securities API
  description: The Securities API from FIXSIM — 1 operation(s) for securities.
  humanURL: https://portal.fixsim.com/swagger/index.html
  baseURL: https://portal.fixsim.com
  tags:
  - Securities
  properties:
  - type: OpenAPI
    url: openapi/fixsim-com-securities-api-openapi.yml
  - type: JSONSchema
    url: json-schema/fixsim-com-security-schema.json
  - type: JSONSchema
    url: json-schema/fixsim-com-new-security-schema.json
- aid: fixsim-com:fixsim-com-sessions-api
  name: FIXSIM Sessions API
  description: The Sessions API from FIXSIM — 3 operation(s) for sessions.
  humanURL: https://portal.fixsim.com/swagger/index.html
  baseURL: https://portal.fixsim.com
  tags:
  - Sessions
  properties:
  - type: OpenAPI
    url: openapi/fixsim-com-sessions-api-openapi.yml
  - type: JSONSchema
    url: json-schema/fixsim-com-session-info-schema.json
- aid: fixsim-com:fixsim-com-sessionsettings-api
  name: FIXSIM Session Settings API
  description: The SessionSettings API from FIXSIM — 1 operation(s) for sessionsettings.
  humanURL: https://portal.fixsim.com/swagger/index.html
  baseURL: https://portal.fixsim.com
  tags:
  - Session Settings
  tags_raw:
  - SessionSettings
  properties:
  - type: OpenAPI
    url: openapi/fixsim-com-sessionsettings-api-openapi.yml
  - type: JSONSchema
    url: json-schema/fixsim-com-session-settings-schema.json
- aid: fixsim-com:fixsim-com-sso-api
  name: FIXSIM SSO API
  description: The Sso API from FIXSIM — 4 operation(s) for sso.
  humanURL: https://portal.fixsim.com/swagger/index.html
  baseURL: https://portal.fixsim.com
  tags:
  - SSO
  tags_raw:
  - Sso
  properties:
  - type: OpenAPI
    url: openapi/fixsim-com-sso-api-openapi.yml
x-enrichment:
  date: '2026-11-08'
  status: enriched
  artifacts_added: 24
  pass: modular-v1
  engine: identity=local,contract=local,surfaces=local,docs=local,regulatory=local

FIXSIM API — frequently asked questions

Does FIXSIM have an API?

Yes. APIs.io lists 10 APIs from FIXSIM, including FIXSIM Executions In API, FIXSIM Executions Out API and FIXSIM Instances API, and 7 more.

Is there an OpenAPI specification for the FIXSIM API?

Yes. APIs.io indexes 10 OpenAPI specifications for FIXSIM, each linked for download from this page.

How do I authenticate with the FIXSIM API?

FIXSIM uses bearer-token authentication (apiKey · 1 scheme). The details are profiled on APIs.io as FIXSIM Authentication.

How much does the FIXSIM API cost?

FIXSIM publishes its prices; its Starter plan is $500/ month as of 2026-11-08. APIs.io lists 3 pricing plans for FIXSIM, with each plan's price, limits and inclusions under Pricing on this page.

Is the FIXSIM API ready for AI agents?

FIXSIM has a Kin Score of 44.2 out of 100 (developing) and an Agent Readiness score of 19.0 (agent-aware), scored by API Evangelist on 2026-11-13.

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