Official vendor OpenAPI document · agent-readyDeveloper ToolsTesting QaapiKey2 EndpointsREST
For Agents
Generate synthetic JSON test data from a schema specification, either one document at a time or in batches. Useful for seeding test environments and demo fixtures.
Use for: I need to generate fake JSON data for a test fixture, Create synthetic test data from a schema, Generate a batch of fake user records for staging, Get a sample JSON document matching this schema
Not supported: Does not validate schemas, store generated data, or anonymise real production data - use for synthetic JSON generation from a schema only.
FakeJSON generates synthetic JSON test data on demand from a schema-style request body. The two endpoints handle a single-document request at /q and a batched request at /q/batch, both authenticated by an API token included in the request body. It is a small but focused tool for filling staging environments, demoing UIs, and running load tests without touching real production data.
Install Jentic One Beta
Connect the FakeJSON API to your agent
Jentic One is a self-hosted execution layer for AI agents. It lets your agent call the FakeJSON API, or any other public or private API you need. You set the rules, the agent never sees your credentials, and every call is logged.
Two steps, two machines. Install the instance in a safe environment, then register your agent from wherever it runs.
1
Step 1: Jentic One Host machine
# On the machine that will host your Jentic One instance:
curl -fsSL "https://jentic.com/install.sh?src=apis&api=%2Fapis%2Ffakejson.com%2Ffakejson" | sh2
Step 2: Agent machine
# On the machine where your agent runs (keep this separate from the instance):
curl -fsSL "https://jentic.com/install.sh?src=apis&api=%2Fapis%2Ffakejson.com%2Ffakejson" | sh
jentic register # connects your agent to your Jentic One instanceJentic One is in public beta. The setup above keeps your agent separate from the instance, which is what you want before using real credentials: an agent running as the same OS user as Jentic One can read its stored keys directly. Just evaluating? A single local install is fine to start. See the secure deployment guide for the tiers.
Capabilities
What an agent can do with FakeJSON API.
Generate a single fake JSON document from a schema specification
Generate a batch of fake JSON documents in one request
Seed a staging or demo environment with synthetic records
Produce structured fixtures for UI prototypes without real user data
Simulate API responses for offline development and testing
Use Cases
Patterns agents use FakeJSON API for, with concrete tasks.
★ Staging Environment Seeding
A QA engineer needs to populate a staging database with realistic-looking but synthetic records before running a smoke test. The agent calls /q/batch with a schema describing user, order, or product objects and writes the response into the staging store. The whole seeding run is one API call regardless of batch size.
POST a batch schema describing 100 user records with name, email, and address fields to /q/batch and write the returned array to the staging users table.
UI Prototype Fixtures
A frontend developer building a prototype needs realistic JSON to render lists and cards before the backend exists. The agent calls /q with a schema matching the UI's expected shape and the response feeds the component as a static fixture. Removes the need to hand-write JSON or scrape sample data from production.
POST a single-document schema describing a product card to /q and write the returned JSON to a fixtures file the prototype reads on load.
AI Agent Test Data Helper
An AI agent helping a developer scaffold a new project uses Jentic to generate fixture data without leaving the chat session. Jentic exposes the /q and /q/batch operations with their schema parameters, and the agent picks the correct endpoint based on the requested record count. Useful in scaffolding and onboarding flows.
Call jentic.search with 'generate fake JSON data', load the /q/batch operation, execute it with the developer's schema and a record count of 50, and return the JSON array.
Key Endpoints
2 endpoints — fakejson generates synthetic json test data on demand from a schema-style request body.
METHOD
PATH
DESCRIPTION
POST
/q
Generate a single fake JSON document from a schema
POST
/q/batch
Generate a batch of fake JSON documents from a schema
POST
/q
Generate a single fake JSON document from a schema
POST
/q/batch
Generate a batch of fake JSON documents from a schema
Jentic AI Readiness Score
This API is usable in Jentic One now. Its AI-readiness score against Jentic's framework shows where it stands today and where improvements would make it even easier for agents to use.
F
FakeJSON API
- Non-Ready (F)0/100
74
Foundational Compliance63
Developer Experience & Jentic Compatibility54
AI-Readiness & Agent Experience94
Agent Usability0
Security100
AI DiscoverabilityPowered by JenticScoring Framework 1.0.0 | Scoring Engine 0.4.0
Show dimension breakdown
74
Foundational Compliance
Base layer of spec validity and structural soundness.
Grade: A-Signals: 4
95%
Lint Results
Aggregated quality score from linter diagnostics, weighted by severity.
100%
Resolution Completeness
Percentage of `$ref` references that resolve successfully.
0%
Specification Validity
Checks whether the API description parses successfully and conforms to its declared specification (e.g., OpenAPI).
100%
Structural Integrity
Structural correctness score based on schema issues using logarithmic dampening.
63
Developer Experience & Jentic Compatibility
Clarity, completeness, and ingestion readiness for developers and tooling.
Grade: B-Signals: 4
0%
Example Density
How richly the API is illustrated with examples.
100%
Example Validity
Percentage of examples that conform to their schemas.
50%
Response Coverage
Percentage of operations with complete response definitions (success, client error, server error).
100%
Tooling Readiness
Health of API ingestion, bundling, and resolution within Jentic pipelines.
54
AI-Readiness & Agent Experience
Semantic breadth, depth, and agent comprehension for AI systems.
Grade: CSignals: 4
67%
Description Coverage
Coverage of descriptions across API elements.
0%
Error Standardization
Coverage of RFC 9457 Problem Details for error responses.
100%
OperationId Quality
Coverage, uniqueness, and casing consistency of operationIds for AI inference.
50%
Summary Coverage
Coverage of summaries across operations/tags/info.
94
Agent Usability
Functional utility, complexity comfort, and AI orchestration readiness.
Grade: A+Signals: 1
94%
Complexity Comfort
Agent comfort level based on API operational and structural complexity.
0
Security
Trust, risk posture, and security compliance.
Grade: FSignals: 1
0%
Authentication Strength
Average quality of security schemes based on authentication method strength (weakest link for OAuth2).
100
AI Discoverability
Findability, semantic richness, and reasoning readiness.
Grade: A+Signals: 1
100%
Descriptive Richness
Clarity and depth of descriptions across API elements.
Score it yourself
Every API in the directory is allowlisted, so you can re-score it with no key required.
npx @jentic/api-scorecard-cli score <openapi-url>Why Jentic?
What agents get from Jentic-routed access to this vendor.
Setup
Wiring the FakeJSON API by hand means placing its token inside the request body, targeting the app.fakejson.com host, and choosing between the single and batch generation routes yourself. Through Jentic you install once, import the FakeJSON API from the API Directory, store the token once, and your agent calls it.
Permission scoping
FakeJSON carries the schema and token in the request body rather than a resource id in the path, so you limit the agent to the operations it needs: generating a single record set with /q or a batch with /q/batch. You choose those operations, so the agent only ever generates synthetic data.
Credential isolation
Your FakeJSON token is stored once, encrypted, by your own Jentic One instance and merged into the outgoing request body at execution time. The token value never enters the agent's prompt, logs, or context.
Intent-based discovery
Agents search Jentic by intent such as 'generate fake JSON data', and Jentic returns the /q and /q/batch operations with their schema parameters so the agent picks single or batch based on the requested record count without browsing the reference docs.
Related APIs
Alternatives and complements available in the Jentic catalogue.
FAQs
Specific to using FakeJSON API through Jentic.
What authentication does the FakeJSON API use?
FakeJSON uses an apiKey passed inside the request body as the token field on the JSON payload. Through Jentic the token is stored encrypted in the vault and injected into outgoing /q and /q/batch request bodies so the agent never sees the raw value.
Can I generate a batch of fake records with the FakeJSON API?
Yes. POST a schema specification along with the desired record count to /q/batch. The endpoint returns the array of generated documents in a single response and is the right choice when you need more than one record.
What are the rate limits for the FakeJSON API?
Rate limits are not declared in the spec. Plans on FakeJSON's pricing page are credit-based per generated record rather than per-second quotas - the token's plan determines monthly throughput.
How do I generate fake JSON through Jentic?
Run pip install jentic, call jentic.search with 'generate fake JSON data', load the /q operation for a single document or /q/batch for many, and execute with your schema. The token is replayed from the vault on each call.
Does FakeJSON return realistic field values?
Yes. The schema fields accept type tokens like 'firstName', 'email', and 'address' that produce plausible synthetic values, which is the main reason to use it over hand-written JSON fixtures.
Is the FakeJSON API free?
FakeJSON offers a limited free tier and paid plans for higher record volumes. The original fakejson.com domain has been redirected and the active host is app.fakejson.com - check current plan terms before relying on it for production-scale fixture generation.
Can I limit what my agent is allowed to do with the FakeJSON API?
Yes. Because you run Jentic One yourself, your own rules decide which FakeJSON operations the agent may call and which credentials it may use. FakeJSON only exposes two operations, generating a single document at /q and a batch at /q/batch, so you can permit just the one your workflow needs and leave the other off. Since the schema and token travel in the request body rather than a path resource, scoping to those operations means the agent can only ever generate synthetic JSON data and nothing else.
GET STARTED