Install Jentic One Beta

Connect the Mermaid API to your agent

Jentic One is a self-hosted execution layer for AI agents. It lets your agent call the Mermaid 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.

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%2Fmermaidchart.com%2Fmermaidchart" | sh

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%2Fmermaidchart.com%2Fmermaidchart" | sh
jentic register       # connects your agent to your Jentic One instance

Jentic 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 Mermaid API.

Validate Mermaid diagram code and get back whether it is valid, the diagramType, and the reason it fails

Render diagram code to svg, png, or pdf by setting the required format field

Control PNG output with scale and background, or set pdf fit to size the page to the diagram

Skip the shared render cache for a single call by sending cache false

Check the key owner's API credit balance and the per-endpoint cost before a batch of renders

GET STARTED

Start building with Mermaid API

Explore with Jentic One

View OpenAPI Document

Use Cases

Patterns agents use Mermaid API for, with concrete tasks.

★ Agent self-checks the diagrams it writes, through Jentic

LLMs often write Mermaid code that almost parses. An agent connected through Jentic sends its draft to the validate operation, reads the error message when the code is invalid, fixes it, and only then calls render to produce the final SVG or PNG. Your Mermaid key stays on your own Jentic One instance, and your rules decide whether the agent may call render as well as validate.

POST /v1/validate with code 'flowchart TD\n A[Start] --> B[Done]'; if valid is false, correct the code from the returned message and validate again, then POST /v1/render with format 'svg'

Diagrams in CI pipelines and docs builds

A docs build can render every Mermaid block to static images instead of shipping a client-side renderer. The render operation takes code and format, returns the image bytes with the matching content type, or a JSON envelope when the request accepts application/json. A failed parse returns ERR_DIAGRAM_INVALID so the pipeline can stop on a broken diagram.

POST /v1/render with code from docs/architecture.mmd, format 'png', and png { scale: 2, background: 'white' }, then save the bytes as architecture.png

PDF exports of diagrams

Product teams that let users download diagrams can render to PDF. With pdf fit set to true the page is the size of the diagram; with fit false the diagram is scaled onto one A4 page, which suits printable reports.

POST /v1/render with the diagram code, format 'pdf', and pdf { fit: false } to produce a one-page A4 PDF

Credit-aware batch rendering

Each keyed call spends API credits from the key owner's balance. Before a large batch, an agent calls the balance operation, which costs no credits, to see the remaining balance and every endpoint's cost, and stops before the allowance runs out.

GET /v1/balance, compare the remaining credits with the number of diagrams queued, and render only as many as the balance covers

Key Endpoints

8 endpoints — the mermaid api validates and renders mermaid diagram code for programs such as agents, llm tool calls, and ci pipelines.

METHOD

PATH

DESCRIPTION

POST

/v1/validate

Validate diagram code

POST

/v1/render

Render diagram code to svg, png, or pdf

GET

/v1/balance

Get the credit balance and endpoint costs

GET

/v1/errors.json

Get the error reference

GET

/health

Check liveness and deployed build

POST

/v1/validate

Validate diagram code

POST

/v1/render

Render diagram code to svg, png, or pdf

GET

/v1/balance

Get the credit balance and endpoint costs

GET

/v1/errors.json

Get the error reference

GET

/health

Check liveness and deployed build

Why Jentic?

What agents get from Jentic-routed access to this vendor.

Setup

Wiring the Mermaid API by hand means handling its bearer key, choosing bytes or JSON-envelope responses per content type, and tracking credit spend. Through Jentic you install once, import the Mermaid API from the API Directory, store the key once, and your agent calls it.

Permission scoping

The Mermaid API carries the diagram and output format inside the request body, so rules bound which operations your agent may call, not which diagrams. Limit the agent to the operations it needs, such as validation, so credit-spending renders are not included unless you add them.

Credential isolation

Your Mermaid API key is stored once, encrypted, by your own Jentic One instance and injected at execution time. It never enters the agent's prompt, logs, or context.

Intent-based discovery

Agents search Jentic by intent such as 'render a Mermaid diagram to PNG' or 'check if Mermaid code is valid', and Jentic returns the matching Mermaid operation with its input schema so the agent calls the right endpoint without browsing the reference docs.

FAQs

Specific to using Mermaid API through Jentic.

What authentication does the Mermaid API use?

Per its OpenAPI spec, the Mermaid API uses a bearer API key (the apiKey scheme) sent as `Authorization: Bearer <key>` on validate, render, and balance. The health, openapi.json, docs, errors.json, and llms.txt reference endpoints need no auth. Through Jentic the key is stored encrypted by your own Jentic One instance and injected when the agent calls.

Can I render Mermaid diagrams to PNG with a transparent background?

Yes. Send POST /v1/render with code, format set to png, and a png object whose background is a CSS colour or transparent. The png scale option sets device pixels per CSS pixel and is lowered automatically when the image would exceed the service ceiling.

How do I validate a diagram through Jentic?

Install Jentic One with `curl -fsSL https://raw.githubusercontent.com/jentic/jentic-one/main/tools/install.sh | sh`, import the Mermaid API from the directory, and store your key. Your agent searches 'validate Mermaid diagram code', gets POST /v1/validate with its schema, and sends the code field. To run it on your own infrastructure, install Jentic One from its GitHub repo.

Can I limit what my agent is allowed to do with the Mermaid API?

Yes. For example, write a rule that allows only POST /v1/validate, so the agent can check diagram code as often as it likes but cannot spend credits on renders. Add POST /v1/render when you want it to produce images, and every call it makes is logged.

Is there a Mermaid MCP server?

You don't need an MCP server to give your agent the Mermaid API. Jentic connects it directly from the API Directory: import it, store your credential once, and your agent calls it.

What are the rate limits for the Mermaid API?

The spec describes a burst limit reported per key in the ratelimit-policy and ratelimit response headers, with retry-after on a 429. Keyed calls also spend API credits: validate and render cost 1 credit each and balance costs 0. The allowance and burst defaults are service configuration, so check the API reference at https://api.mermaid.ai/v1/docs for current values.

Is the Mermaid API stable?

No, it is in beta. The spec states that request and response fields, defaults, and limits may change and the Mermaid version can bump without notice, while the /v1 prefix, the error structure, and bearer authentication stay fixed. Every response carries the x-mermaid-api-phase header with the value beta.

Mermaidchart Mermaid API

AI ReadinessAI-Aware (B+)69/100

See full scorecard

Official vendor OpenAPI document · agent-readyMediaImage Processingbearer8 EndpointsREST

For Agents

Validate Mermaid diagram code and render it to SVG, PNG, or PDF so an agent can check and ship the diagrams it writes.

Use for: Check whether this Mermaid flowchart code is valid before I commit it, Render a sequence diagram to PNG with a transparent background, I want to turn Mermaid code from my README into an SVG, Export an architecture diagram as a PDF sized to the diagram

Not supported: Does not store diagrams, host a diagram editor, or render other diagram languages such as PlantUML. Use for validating and rendering Mermaid code only.

The Mermaid API validates and renders Mermaid diagram code for programs such as agents, LLM tool calls, and CI pipelines. The validate operation reports whether diagram code parses and, if not, why, along with the detected diagramType. The render operation turns the same code into SVG, PNG, or PDF, with PNG options for scale and background and a PDF fit option, using the latest Mermaid release. A balance operation shows the key owner's remaining API credits and what each endpoint costs.

Jentic One on Github View OpenAPI Document

Show dimension breakdown

Foundational Compliance

Base layer of spec validity and structural soundness.

Grade: A+Signals: 4

99%

Lint Results

Aggregated quality score from linter diagnostics, weighted by severity.

100%

Resolution Completeness

Percentage of `$ref` references that resolve successfully.

100%

Specification Validity

Checks whether the API description parses successfully and conforms to its declared specification (e.g., OpenAPI).

75%

Structural Integrity

Structural correctness score based on schema issues using logarithmic dampening.

Developer Experience & Jentic Compatibility

Clarity, completeness, and ingestion readiness for developers and tooling.

Grade: BSignals: 4

Example Density

How richly the API is illustrated with examples.

100%

Example Validity

Percentage of examples that conform to their schemas.

62%

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.

AI-Readiness & Agent Experience

Semantic breadth, depth, and agent comprehension for AI systems.

Grade: C-Signals: 4

55%

Description Coverage

Coverage of descriptions across API elements.

Error Standardization

Coverage of RFC 9457 Problem Details for error responses.

100%

OperationId Quality

Coverage, uniqueness, and casing consistency of operationIds for AI inference.

47%

Summary Coverage

Coverage of summaries across operations/tags/info.

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.

Security

Trust, risk posture, and security compliance.

Grade: B-Signals: 1

60%

Authentication Strength

Average quality of security schemes based on authentication method strength (weakest link for OAuth2).

AI Discoverability

Findability, semantic richness, and reasoning readiness.

Grade: ASignals: 1

88%

Descriptive Richness

Clarity and depth of descriptions across API elements.

Connect the Mermaid API to your agent

Capabilities

Start building with Mermaid API

Use Cases

Key Endpoints

Why Jentic?

Related APIs

FAQs

Mermaidchart Mermaid API

Jentic AI Readiness Score

Mermaid API

Foundational Compliance

Lint Results

Resolution Completeness

Specification Validity

Structural Integrity

Developer Experience & Jentic Compatibility

Example Density

Example Validity

Response Coverage

Tooling Readiness

AI-Readiness & Agent Experience

Description Coverage

Error Standardization

OperationId Quality

Summary Coverage

Agent Usability

Complexity Comfort

Security

Authentication Strength

AI Discoverability

Descriptive Richness