INPUT
0 marked
FIND
ADVERTISEMENT
AD SLOT
160 × 600
160 × 600
OUTPUT
FIND
Beautify, minify, validate and convert JSON — flag lines, your JSON never leaves your browser
CTRL+ENTER format CTRL+F findJsonSilk formats, validates and minifies JSON entirely in your browser — and lets you flag the lines you are working on, so you never lose your place in a long file. It is built around a single goal: working with JSON should feel effortless.
Click any line number and it gets a mark. The header keeps a count, and prev and next jump you between marked lines, so you can move through the places you care about without scrolling past everything in between. Clear wipes them all when you are done.
The marks follow the content, not the line number. Insert ten lines above a marked row and the mark moves down with it, still on the value you flagged. Delete that row and the mark goes with it. This is the difference between an annotation you can trust and one you have to re-check every time you edit.
It is a scratch annotation layer for a document you will only have open for ten minutes: the lines you have already fixed, the ones you still need to check, the three values a colleague asked about. Working through a long config file without losing your place is the thing this tool was built to make easy, and it is the part we would miss most if it were taken away.
There is no server. JsonSilk is a static page: the parsing, formatting and converting all happen in the tab you have open, on your own machine. No account, no sign-up and no upload step.
You do not have to take our word for it. Open your browser's developer tools, switch to the network panel, then paste a payload and format it: nothing is sent. Or disconnect from the network entirely and keep working — everything still runs, because there is nothing on the other end to talk to.
What is kept locally, and only locally: your theme choice, your indent and sort preferences, and whether you have seen the demo. Those live in your browser's own storage so the page remembers them next time. They never go anywhere. That is the whole list — we would rather tell you exactly what is stored than claim nothing is.
Most tools give up on a big file: they refuse it, truncate it, or quietly turn the editor read-only so all you can do is look. JsonSilk keeps it editable. A five megabyte document still types at full speed — including through an IME, which is where browser text areas fall apart worst.
Formatting, validating and searching hold up far past that. Tens of megabytes come back in seconds, and a sixty megabyte document still opens, formats and searches — because the parsing runs on a background thread and the editor only ever draws the few dozen lines you are actually looking at, however long the file is. The tree and table views cost more per row, so past a few megabytes JsonSilk gives you an estimate first and lets you decide — a number, not a spinner.
Each pane has its own search box, so you can look for different things on each side at the same time. Matches are highlighted inline, with a counter and up/down navigation — and the line numbers of matching rows light up in the gutter, so you can see where the hits are without scrolling to them. In a nine-hundred-line document that turns "where is this key" from a hunt into a glance.
Both boxes take a regular expression when you tick Regex, so you
can search for a shape rather than a string — every ISO timestamp, every empty
string, every key that ends in _id. Match case still applies,
and a half-typed pattern says so instead of quietly reporting no matches. Leave the
box unticked and your text is matched literally, dots and brackets included.
The pattern follows you between views. The same box drives the text, tree, table and mind map views, so a regular expression you wrote while reading the raw JSON keeps working when you switch to the tree to see where the matches sit, or to the table to read them as rows. You write it once.
Format re-indents with two spaces, four spaces or tabs; the beautified output can also have every object's keys sorted recursively, which makes two versions of the same payload easy to diff. Minify strips all whitespace to a single line, with the result wrapped so you can read it instead of scrolling sideways forever — a five megabyte payload minifies to one line millions of characters wide, and no browser will draw that. Syntax errors report the line, the column and the actual reason — trailing comma is not allowed in JSON, single quotes are not valid in JSON — and clicking the message jumps your cursor straight to the character. While the input is broken the last valid output stays on screen instead of blanking out.
JsonSilk uses its own parser rather than the browser's JSON.parse,
so every value is written back exactly as you typed it. A twenty-digit integer
stays intact instead of silently rounding, 1e400 stays
1e400 instead of turning into null, and escape sequences
are not rewritten. If you are inspecting API payloads, financial records or IDs
that happen to look like big numbers, this is the difference between reading your
data and reading a lossy copy of it.
The output pane has four views and they share one search box. Text is the formatted JSON. Tree collapses and expands so you can take in the shape of a document without reading every value; searching marks the branches that have matches inside, and leaves the expanding to you. Table lays an array of objects out as rows and columns — the same projection the CSV download uses, so what you see is exactly what you would save.
Mind map draws the same document as cards joined by labelled lines: one
card per object or array, one row per field, and a line out to every nested object
with its key printed on it. It answers a different question from the tree — not
“what is inside this branch” but “how is this document shaped”. Scroll to move
around, hold Ctrl and scroll to zoom, or drag the canvas with the
mouse; press 0 to fit the whole map on screen. Collapsing works exactly as it does in the tree, and the two views share the
same collapsed branches, so what you opened in one is already open in the other.
Values stay selectable text in the colours the other views use, because the cards
are ordinary HTML rather than pixels on a canvas.
You can take the map with you. Download Mind Map saves exactly what is on screen — collapsed branches, search highlights and the theme you are using included. SVG is vector, so it stays sharp at any size, the text in it is still text you can search and select, and there is no size limit. PNG is the one to paste into a pull request, a ticket or a slide deck. Very tall maps go past what a browser can hold as a bitmap; when that happens JsonSilk tells you the size it would have needed and points you at SVG, rather than quietly saving a blank or half-drawn image.
Both files are drawn from the document itself, in your browser — not screenshotted, so the whole map comes out, not just the part scrolled into view, and nothing is uploaded to produce it. A map that is sixty thousand pixels tall exports as one complete SVG.
The table loads two thousand rows at a time, with Next and Show all at the bottom telling you exactly how many are left. There is no cap: a hundred thousand rows are all reachable, you just decide when to pay for them. Searching still covers every row, loaded or not — jump to a match beyond what is on screen and the rows it needs arrive with it.
The table view adds a second copy button. Copy JSON gives you the text exactly as the text view shows it; Copy table (TSV) puts every row on your clipboard ready to paste into Excel or Google Sheets — tab-separated, so the columns land in columns instead of all in one cell. It copies the whole table, not the part you have scrolled into view, and values containing tabs or line breaks are quoted so a single awkward field cannot shift the rest of the row.
There are two ways to get more room and they stack. The full screen button in the header hands the page the entire display: the address bar, the tab strip and the bookmarks all go away, which on a laptop is usually another hundred and fifty pixels of JSON. The widen button above the output pane does something different — it folds the input pane away so the output takes the full width, without leaving the browser. The action buttons stay put either way, so you can still format, search and download with the input pane folded away.
Full screen is the browser's own, so F11 and Esc work
as they always do, and leaving from the browser's menu works too. However you go in
or out, the button follows — it never sits there claiming you are full screen when
you are not. On a browser that will not allow it, the button is simply not shown,
rather than being there and doing nothing.
Download saves the formatted JSON, or converts it first. CSV output carries a
UTF-8 byte order mark so Excel opens it without mojibake. XML output sanitises
element names that JSON allows but XML does not, keeping the original key in a
name attribute so nothing is lost. The table view shows you the same
projection the CSV uses, so you can check it before you save.
A tool earns its place through details. The pause before re-formatting grows with the size of your document, so it never fights your typing. Line numbers re-align themselves when a minified line wraps. Your last valid output stays on screen while you fix a syntax error, rather than the pane going blank. Clicking an error message puts the cursor on the exact character. One button sends the formatted output back into the input pane, so you can carry on editing it instead of copying between panes. Undo and redo work properly, over the whole editing history, not just the last thing you typed. The JSON text has its own size control, so you can make the code bigger without blowing up the rest of the page the way the browser's zoom does. None of these are headline features — together they are what we mean by silk, and they are the part of the product we keep coming back to.