Best Free AI Tools for Developers (September 2026)

Most "free AI tools" are free trials with a credit card wall. These aren't. Every tool on this list works right now in your browser. No signup. No API key. No 14-day countdown.

Comparing model pricing across dozens of models shouldn't require a spreadsheet. Converting a CSV to JSON shouldn't require installing pandas. Here are the tools, organized by what they actually do.

Model Comparison and Selection

Benchmark Dashboard

Compare every model we track on intelligence, real cost per task and response time in one chart. Data comes from Artificial Analysis, updated when new models drop, with a switch between everyday and max reasoning effort.

Filter by task, sort by any metric, and see which models sit on the frontier where nothing cheaper scores higher.

Try it: Benchmark Dashboard

Model Selector

Pick the tasks you use AI for and whether you care most about quality, value or speed. You get one model per task with its monthly cost, plus an OpenClaw config to paste.

Faster than scrolling through the benchmark dashboard when you just need a quick answer to "which model should I use for X?"

Try it: Model Selector

Cost Calculator

Estimate your monthly AI bill for any model, per task and in total. Costs include thinking tokens, which is where cheap-looking models often get expensive.

We covered the cost optimization strategies in detail in our guide to reducing AI API costs. The calculator makes those estimates concrete.

Try it: Cost Calculator

Token Counter

Paste text and see estimated token counts for different models. Helpful for estimating costs, staying within context limits, and understanding why some prompts cost more than others.

Different tokenizers produce different counts. A 1,000-word prompt is about 1,300 tokens with an OpenAI model, while Anthropic's docs put Claude's current tokenizer at roughly 555,000 words per million tokens, or about 1,800 per 1,000 words (Anthropic). The counter shows a count for each model: exact for GPT-5 models, estimated for the rest.

Try it: Token Counter

Data Conversion Tools

Text to CSV Converter

Paste text, pick a delimiter, download a CSV file. Auto-detects tabs, commas, pipes, semicolons, spaces and "Name: value" lines. The standard conversion runs in your browser, so your data never leaves your machine.

Includes AI Smart Parse for messy data that doesn't follow a consistent delimiter pattern. It's the one feature that sends your text to a server, and only when you click it. We covered all five conversion methods in the text-to-csv guide.

Try it: Text to CSV

CSV to Text Converter

The reverse of the above. Turn CSV data into a readable table, a list, labeled records, Markdown or your own template.

Try it: CSV to Text

CSV to JSON Converter

Upload CSV, get a JSON array of objects, arrays, a keyed object or JSON Lines. Each CSV header becomes a JSON key, numbers stay numbers, and address.city headers become nested objects. Handles quoted fields and files up to 10 MB. We wrote a full guide on CSV to JSON conversion if you need batch or custom approaches.

Try it: CSV to JSON

JSON to CSV Converter

The reverse. Flatten JSON arrays into downloadable CSV files. Handles nested objects by creating dot-notation column headers.

Try it: JSON to CSV

JSON Formatter

Paste messy JSON, get it formatted with proper indentation. Also minifies JSON for production use, validates syntax, points to errors, and repairs broken JSON from logs and chat replies.

Try it: JSON Formatter

Markdown to HTML Converter

Convert Markdown to clean HTML. Useful for email templates, CMS content, and documentation that needs to render as HTML.

Try it: Markdown to HTML

PDF to Markdown Converter

Extract text from PDF files and convert it to Markdown, with headings detected from font size. It runs in your browser and doesn't do OCR, so scanned PDFs need a vision model instead. Good for converting documentation or research papers into editable formats.

Try it: PDF to Markdown

CSV Cleaner

See a health report first, then remove duplicate rows and blank rows, trim whitespace, delete empty columns and flag invalid-looking emails. Clean your data before importing it somewhere else.

Try it: CSV Cleaner

Image Converter

Convert up to 20 images at a time between formats (PNG, JPEG, WebP) and resize them. Useful for optimizing images for web performance without installing ImageMagick.

Try it: Image Converter

AI Writing and Prompt Tools

Prompt Optimizer

Paste a rough prompt and it checks it against seven basics as you type, such as task, output format and audience. Then pick a rewrite style (clearer, more detailed, shorter or structured) and AI rewrites it and shows every change.

Try it: Prompt Optimizer

Humanize AI Text Tool

Make AI-generated text sound human. Removes common AI tells: em dashes, buzzwords, rule-of-three patterns, overly uniform sentence lengths. It rewrites up to 5,000 characters per run in the tone you pick.

Cheap models tend to produce text that reads like a press release. The humanizer strips the AI fingerprint without losing the content.

Try it: Humanize Text

Prompt Library

Browse and copy 18 system prompts and agent configs for coding, code review, SQL, writing, email triage, support and research. Each has fill-in fields, a token count and a model pick.

Try it: Prompt Library

FAQ

Are these tools really free?

Yes. No trial period, no credit card, no signup. The AI-powered features (Prompt Optimizer rewrites, Humanize Text, AI Smart Parse) use our API quota, so they have rate limits. Everything else runs entirely in your browser.

Do these tools store my data?

No. The data conversion tools (CSV, JSON, text, image) run 100% in your browser. Nothing is sent to a server. The AI-powered tools send your text to an AI API for processing, but nothing is stored. See our privacy policy for details.

Which tool should I start with?

If you work with AI models: the Benchmark Dashboard. If you work with data: the Text to CSV or CSV to JSON converter. If you write AI prompts: the Prompt Optimizer.

Can I use these tools on mobile?

Yes. Every tool is responsive and works in mobile browsers. The data conversion tools work particularly well on tablets for quick file conversions.

All tools are free and available at dervity.com/tools. Model data sourced from Artificial Analysis Intelligence Index v4.3.2. Updated September 26, 2026. For choosing the right AI model for your work, see our Best LLM in 2026 guide and the LLM Leaderboard.